Play Free Live Casino
Top 10 Casino Sites

The Top Online Casinos With The Best Bonus Slots Features

Gaming providers have always tried to find new and innovative ways to keep the punter entertained, and this has resulted in some of the best bonus slots features currently available.

These are in-game extras that offer an additional way of winning. They range from special symbols and free spins to mini-games, jackpots and more.

The Top Casinos With The Best Bonus Slots

  • Over 2400 games including bonus slots
  • 1000+ bonus slots to play on mobile devices
  • 90+ top providers including NetEnt & Play’n GO
100% new player bonus & free spins
Play * more terms & conditions apply
  • Regular promotions incl. Drops & Wins and tournaments
  • Bonus slots from 40+ providers
  • 200+ bonus buy feature slots available
100% up to £300 & 150 free spins
Play * more terms & conditions apply
logo Spinia
  • 2000+ slots from over a dozen leading providers
  • Fast deposits & withdrawals via a dozen banking options
  • Regular free spins promotions & reload bonuses
100% up to £250 for new sign-ups
Play * more terms & conditions apply
  • 1000+ big-name slots from major providers
  • Over 70 progressive slots with big-money jackpots
  • Regular slot tournaments with cash prizes
150% up to £500 & free spins
Play * more terms & conditions apply
logo Mr Bit
  • Top-name slots from Microgaming, NetEnt, and more
  • Must-Drop jackpots running every hour
  • Cashback and player points for all customers
125% up to £50 & 50 free spins
Play * more terms & conditions apply
logo PlayFrank
  • Daily challenges and regular rewards
  • Over 900 slots from NetEnt, Play’n GO & more
  • Big-name Megaways slots like Dragon Luck Megaways
100% up to £100 & 50 free spins
Play * more terms & conditions apply
  • 1500+ slots including big bonus games
  • 12+ developers offered including NetEnt
  • High Roller bonuses available
100% welcome bonus plus free spins
Play * more terms & conditions apply
logo CasinoFriday Review
  • Fast withdrawals
  • Game of the week
  • Loyalty program for high rollers
100% welcome bonus & 200 free spins
Play * more terms & conditions apply
  • 4000+ games from 40+ providers
  • Weekend boosters for winning players
  • Big-money slot offers like The Wheel of Jackpots
100% up to £200 & free welcome spins
Play * more terms & conditions apply
  • 1000+ top online slots from developers incl. Microgaming
  • 100+ jackpot slots including Mega Moolah
  • Weekly bonuses like free spins and Drops & Wins
100% up to £100 & 300 free spins
Play * more terms & conditions apply
  • Hundreds of online slots plus exclusive Bitcoin titles
  • Lots of regular promotions incl. no-deposit bonuses
  • Instant deposits & withdrawals via Bitcoin
Welcome bonus up to 1.5BTC & free spins
Play * more terms & conditions apply
logo SlotsPalace Casino
  • 2000+ biggest online slots from 30+ developers
  • Achievements-based rewards programme
  • 1000+ top slots to play on mobile phones
100% welcome offer for new customers
Play * more terms & conditions apply
  • Established Bitcoin casino with 1500+ games
  • 45 top developers including Microgaming and BetSoft
  • Regular prize giveaways & slot tournaments
100% welcome bonus including free spins offer
Play * more terms & conditions apply
logo Drift Casino
  • 100s best bonus slots by Microgaming, Barcrest & more
  • Big VIP programme and cash back offer
  • Lots of network promotions and cash giveaways
125% up to £500 & 50 free spins
Play * more terms & conditions apply
logo Wildz Casino Review
  • 1000+ slots & games from 25+ developers
  • 90+ Daily Jackpot slots available to play
  • Over a dozen Mega Jackpot titles like Hall of Gods
100% up to £500 & 200 free spins
Play * more terms & conditions apply


What Are Slot Bonus Features?

Most modern online slots come with slot machine bonuses. A slots bonus is an extra feature that gives you a chance of making money alongside your regular spins. It can be as simple as free spins or wild symbols, or it may feature complex multipliers which enhance your payout.

Like all casino games, slots have a return-to-player percentage (RTP). The best bonus slots features help improve the overall RTP of a game.

However, slots with bonus games tend to be volatile. You may experience a few losing spins before triggering slot machines bonuses.

At Top10-CasinoSites, we only feature the best bonus feature slots for you. We recommend the top casinos offering the best slot bonus games in 2021. Plus, we only rate and review legit online casinos licenced by approved bodies like the Malta Gaming Authority and the UK Gambling Commission. Play safely and claim the best online slots bonus codes in comfort.


What is The Difference Between Slot Bonus Feature and a Casino Bonus?

It’s important to understand the difference between the best bonus slots features and an online casino promotion.

A slots bonus round is a feature contained within the game. It can be triggered at random or by landing special symbols during a spin. The best slot bonus rounds should be easy to understand, whatever your level of experience.

The best bonus slots features include free spins where you can enjoy extra games at no cost. Free spins sometimes come with multipliers attached which enhance every winning spin.

You can play free online slots at the best online casino sites to get a feel for the game’s volatility. This is the general frequency with which an online slot triggers its bonuses. By trying out many games, you can figure out the best slots for a bonus feature.

Slots bonuses shouldn’t be confused with a casino slots bonus. This is a separate promotion offered by the online casino. The top UK online casinos usually spread a good variety of offers for players, such as an online slots welcome bonus including a deposit match or free spins on the latest games.

Always look out for the casino terms and conditions when online slots gambling. Bonuses will usually carry strict play-through requirements where you must wager your winnings several times over before withdrawing them.

The Different Types of Slots Bonus Features

So, what slot machines have the best bonuses? You’ll find plenty of top bonus games at the best real-money slots sites. Each slot features a different set of bonuses, while some providers boast unique features you won’t find anywhere else.

As online slot technology improves, so does the breadth of bonus features. Here are some of the best bonus slots features you can enjoy in 2021.

  • Wilds

Wild Wild Riches Slot

Wild symbols can be found in the best paying slot games. Essentially, wilds are like jokers which replace all other regular symbols on the reels. They help to complete unfinished paylines, resulting in a cash payout. Wilds can also contain multipliers which may double or triple your win.

Many modern slots feature neat twists on the conventional wild symbol. Walking wilds, or ‘shifting wilds’, move along the reels one spin at a time until they are removed. They become active on every spin where they are visible.

Expanding wilds, meanwhile, will stretch to fill the entire reel they sit on. This creates more wilds and even more chances to win.

You’ll also find stacked wilds in more generous online slots. These are groups of wild symbols that can appear stacked on top of one another on the same reel. It can be quite lucrative if you manage to land stacked wilds on adjacent reels. And in slots that use more than one reel set, you may find replicating wilds or transferring wilds. When they appear on one reel set, they will copy over to the same position on every other reel set.

  • Scatters

Vikings Go Berzerk Slot

Scatter symbols are the bread and butter of most modern online slots. Scatters are special symbols that pay out a prize wherever they land on the reels. They don’t have to form part of a winning combination in order to pay.

However, the best bonus slot features are usually triggered by landing 3 or more scatters in any position.

  • Multipliers

Drive Multiplier Mayhem

Multipliers can appear in various forms in a slot. A multiplier is one of the best bonus slots features as it can appear during the base game as well as during a feature. Multipliers simply increase the payout for a winning spin. A multiplier may come when you land multiple wilds, or they may appear as standalone symbols on the reels.

You can also enjoy multipliers in a slot that has cascading reels. Your multiplier will increase on every winning cascade, and it will keep increasing as long as you hit consecutive winning spins.

  • Free Spins

Free Spins Slot logo

Free spins is one of the best bonus slots features around. It’s also one of the most common bonuses found in today’s slots.

You can normally trigger free spins by landing 3 or more scatters in any position. You’ll win a set number of free games, and you might earn a multiplier on every winning spin. Some slots even let you choose your own free spins total and multiplier value before you begin.

Best of all, big bonus slots let you retrigger free spins by landing further scatters during the feature.

  • Cascading Reels

Gonzo's Quest Slot

Cascading reels is a feature found in many of the best bonus slots games. After a spin, any connected symbols are removed from the reels, allowing the symbols above to fall into their place. This has the potential of creating even more winning combinations.

Many cascading reels slots install a free re-spin after every successful cascade. You may also earn yourself a multiplier that is applied to your payout.

Cascading reels has been adopted by many of the top slots developers. Whether it’s Avalanche Reels or Tumbling Reels, the mechanic is the same.

You can even enjoy cascading reels in the best Megaways slots online. Play thousands of win lines on every spin and enjoy a re-spin after every successful cascade.

  • Gamble Feature

Gladiator Slot

The gamble feature is a common bonus found in lots of older slots and many new 5-reel games.

The bonus is triggered following a winning spin. You’ll be given the chance to double your win or risk the lot by playing a game. In some games, you may even have a chance to quadruple your winnings.

Gamble features vary, but usually involve correctly guessing the colour of the next card drawn. If you guess correctly – red or black – you’ll double your win. If you guess wrong, you lose all of your winnings for that spin.

You can sometimes find ladder gamble features too. These bonuses give you the chance of moving up a prize ladder by stopping the flashing light in the right place.

  • Wheel of Fortune

Wheel of fortune slot

The wheel of fortune is one of the best bonus slots features for big prizes. It can also be used to determine free spins, multipliers, or jackpots.
Although the wheel of fortune features heavily in land-based slots, particularly games from IGT, it’s also been adopted by online casino games.

When you trigger the wheel, it will spin and come to rest at random. You will win cash, spins, or a multiplier depending on what is displayed on-screen.

  • Nudge Feature

The nudge feature was a popular bonus found in British fruit machines. However, it’s since been adopted by online developers.

The nudge feature triggers at random after any spin. You then have the option of shifting a reel of your choice up or down to help form a winning payline.

  • Split Symbols

Split symbols first appeared in IGT slots, but now feature in games by many other developers. These are special double symbols that appear on the same reel position. Some games even feature triple symbols which can boost your 5-of-a-kind to 8-of-a-kind or higher.

  • Instant Win

The instant win feature can be found in some 5-reel slots. It’s also known as a ‘Click Me’ feature.

The instant win triggers at random after any spin. You’ll have a choice of symbols to click on on the screen. You’ll win a cash sum depending on the symbol you pick.

  • Trail Bonus

The trail bonus originated in UK fruit machines but also appears in some online slots. It’s particularly popular in games like Barcrest’s Rainbow Riches and adds some variety to the game experience.

In a trail bonus, you roll a set of dice and progress along a path containing rewards like cash, free spins, or multipliers. You can usually win a prize jackpot if you make it to the end of the path without ending the feature.

  • Free Re-Spins

Even if you don’t trigger free spins, you may activate a single re-spin during the base game. Re-spins are a common feature of cascading reels slots. Simply hit a winning combination and earn a free re-spin until you hit no more winners.


Different Ways to Win an Online Slots Bonus

1. Win Both Ways

Yokozuna Clash Slot

In win both ways slots, paylines run both left-to-right and right-to-left. This means you can hit winning combinations by matching symbols running from reel 1 or reel 5. It gives you a lot more scope to hit big winners, and these slots tend to be quite low-volatility.


2. 243 Ways to Win

Immortal Romance Slot

Microgaming was one of the first slots developers to implement the 243-ways-to-win system. It’s now used by many top slot developers.

In a 243-ways-to-win slot, payouts are made when you match 3+ symbols anywhere on adjacent reels starting from the left. The system works a little differently from traditional set paylines.

Instead of placing a stake per line, you place a wager covering all possible ways to win. This is usually worth around 30x your coin bet, but the amounts can vary.


3. 1024 Ways to Win

Arctic Fortune Slot

1024 ways to win is an upgrade from 243 ways to win. This betting system is normally found in slots with more than 3 rows.

Again, you must match at least 3 symbols anywhere on adjacent reels, starting on the far left. You pay a set stake to begin with, which covers every possible win line on the screen.


Buy a Bonus

There are many ways to trigger the best bonus slots features. However, there are now more opportunities to activate bonuses without landing scatters.

The ‘Buy Bonus’ feature, or ‘Feature Buy’, is appearing more and more in today’s online slots. Essentially, this feature lets you automatically trigger a bonus round without having to hit scatters or other qualifying symbols. You will also have to pay an additional stake in order to buy the feature.

You’ll find hundreds of slots where you can buy a bonus first. Just click on the Buy Bonus icon prior to playing your game. Pay the required stake and choose which bonus you want to skip to.

Of course, there is no guarantee you will win but it’s one of the best slot bonus rounds for high rollers wanting to cut straight to the action.
It’s worth noting that the buy feature is now banned in the UK. However, while bonus buy slots features are banned, you can still enjoy the same games with the mechanic removed.

You’ll also find bonus buy slots with free play at many top online casinos. Try a buy feature slots demo in the UK and see what all the fuss is about.


Progressive Jackpots

If you love online slots for real money, the next step is to try the best jackpot slots. Progressive jackpots feature in the best slots for bonus payouts. They are normally linked between hundreds of casinos handling millions of spins. And the more people who play the games, the bigger the jackpots.

A progressive jackpot is formed of a small percentage of every qualifying bet, usually around 0.5-1%. The jackpot can trigger at random or be awarded via a special bonus game.

Look for established progressives from developers like NetEnt and Playtech. These games boast the best slot bonus rounds where you might trigger a jackpot worth over £1m.

While some progressives are unlocked at random, others must be win by playing a game. Playtech’s Age of the Gods range features a pick’em game where you must select mystery symbols. Match 3 symbols to win one of the corresponding jackpots.

Microgaming’s legendary Mega Moolah slot works in a similar way. A bonus wheel feature is triggered at random after any spin. Spin the wheel and line up the prize arrows to win one of four amazing jackpots. The top Mega jackpot seeds at a cool £1 million, making Mega Moolah one of the most popular slots in town.


How to Take Advantage of Slots Bonus Features

There are many ways to enjoy the best bonus slots features. Remember that a casino slots bonus is very different from a bonus feature you can trigger within the slot itself.


How to Claim a Slots Bonus

All good UK casinos offer slots promotions to their customers. You can earn a deposit match offer as soon as you register your account. Just choose from one of our best first deposit bonus casino sites to get started.

First, make a first deposit to earn the same amount in bonus funds. In order to clear the funds, you will have to meet the wagering requirements. You’ll usually have to wager your funds 20-40 times over. However, you can take your pick of the best spin games or best bonus buy slots. The casino will release your winnings if you meet the bonus terms within the agreed time limit.

Alternatively, you can pick a top free spins casino bonus. You’ll be given slots online bonus free spins to use on selected games. Any winnings must be wagered according to the terms and conditions.

It is possible, however, to find an online slots bonus with no wagering. These offers tend to be smaller than regular online casino promotions.

You can also claim an online slots bonus with no deposit required. Open your account and receive free casino cash to use on games of your choice. Play free slot games with bonus spins or hit your favourite classic fruit machines. Whatever you choose, you can enjoy the best bonus slots with no deposit needed.

It’s a good idea to choose the best online slots to win a cash prize. Find the best online slots for payout percentage before you begin.


How to Trigger a Slots Bonus

Online slots features work in a different way from casino bonuses. You can trigger the best slot bonus features by landing scatters or using the Buy Feature option.

However, most modern online slots feature a lot of randomly triggered modifiers that can enhance your gameplay. Land wilds, bonus multipliers, or random re-spins for a quick way of earning extra cash.


What Affects Slot Bonus Features?

Games with the best slots bonus features may seem generous, but it’s important to understand the mechanics first. After all, casinos aren’t just going to give away prizes for nothing. You may have to spend a large chunk of your bankroll to enjoy some success.

Here’s what to look for in a game when hunting out the best bonus slots features:

RTP: The RTP (Return to Player percentage) is the average, long-term return made to players over millions of spins. You’ll find a list of the highest slot RTPs on our site.

For example, a slot with an RTP of 97% will – on average – pay out £97 for every £100 paid in. Of course, you may hit a winning streak and enjoy a return on your investment over 100%. But in the long run, you will always lose money playing online slots.

RTPs are calculated based on the arrangement of symbols on the reels. A slot with lots of bonus scatters and wilds will have higher RTPs. It’s also important to know which reels the higher-paying symbols are found on.

Volatility: All slots have an in-built volatility. Essentially, slots volatility is the frequency with which you hit winning spins. So, a game with a low volatility pays out small and frequent prizes. A slot with high volatility pays out large jackpots but very rarely.

Games with the best bonus slots features tend to have higher volatility. You might not win much during the base game but once you trigger a bonus, you may end up hitting a big score. Always find the easiest slot to get a bonus before you start gambling.

Paytable: Always check the paytable before playing. This is where you’ll find details on RTPs and symbol payouts. You can usually gauge whether a slot is volatile or not by reading the payouts for five of a kind. If the biggest-paying symbols have enormous jackpots, it’s a sign they won’t be triggered all that often.

Paylines: Most online slots have fixed paylines. You may have to spread your stake over 20 or more lines on each spin. But by covering more win lines, you'll have a better chance of hitting that elusive bonus feature.


The Best Online Slot Games With Bonus Features

Wild Wild Riches

Wild Wild Riches slot

RTP: 96.77%
Winlines: 576
Minimum Bet: 0.25
Maximum Bet: 48.00
Bonus Features? Yes
Jackpot? Yes

Pragmatic Play’s Wild Wild Riches is a slick Irish-themed slot played on a staggered set of reels. There are 576 ways to win in total and you have the option of betting up to £48 on every spin.

During the game, you can land special money symbols on the reels. These contain a random cash value that can be unlocked if you also land a wild on the screen at the same time.

In addition, you can trigger a free spins round by landing wilds on reels 1 and 2 with a bonus symbol on reel 3. Additional money symbols and wilds give you a bigger chance of landing a cash prize.

But Wild Wild Riches is elevated to legend status by its three giant jackpots. You can win the Mini, Major, or Mega jackpot by landing the respective pot of gold on the screen. Give the game a spin at our top-rated UK casinos and see if you have the luck of the Irish.



Reactoonz Slot

RTP: 96.5%
Winlines: Win clusters
Minimum Bet: 0.20
Maximum Bet: 200.00
Bonus Features? Yes
Jackpot? Yes

Play’n GO already had a hit on their hands with Energoonz but decided to upgrade the smash with Reactoonz.

You play Reactoonz on a 7×7 grid filled with colourful and cute aliens. You win cash by lining up clusters of matching aliens on the reel grid. Winning clusters then explode and disappear from view, allowing free symbols to fall into their place.

Hitting consecutive winning clusters is the key to success. For every win, you’ll fill a notch in the meter to the left of the reels.#

Once the meter fills up, you’ll trigger a special feature that is added to the reels. Symbols may turn into wilds, or low-value symbols may disappear from the screen to leave high-paying ones behind.

Cluster win slots are always a hit with players due to the cascading reels mechanic and potential for bonus payouts. Find the game at casinos with the best bonus slots in 2021.


Piggy Riches

Piggy Riches Game

RTP: 96.38%
Winlines: 15
Minimum Bet: 0.15
Maximum Bet: 75.00
Bonus Features? Yes
Jackpot? Yes

Scandinavian developer, NetEnt, are known for their high-volatility, high-action slots. And in Piggy Riches, NetEnt have combined volatility with big bonuses like free spins, wilds, and multipliers.

Piggy Riches is played with 15 paylines across 5 reels. Wild symbols can land to substitute for all regular symbols in the game. In addition, wild symbols will treble any winning combination they help to complete.

One of the best bonus slots features is the free spins bonus which you can trigger with 3 or more Colosseum-shaped scatters on any position. There’s a maximum of 28 free games for activation, with a maximum multiplier worth 6x.

NetEnt may have produced slicker online slots, but Piggy Riches is ideal if you love the best bonus slots features. Play for free at our top-rated casinos.


Money Train 2

Money Train 2 Slot

RTP: 96.4%
Winlines: 40
Minimum Bet: 0.10
Maximum Bet: 20.00
Bonus Features? Yes
Jackpot? Yes

Money Train 2 is an excellent steampunk-themed sequel to Money Train from Relax Gaming. While it starts with an RTP of 96.4%, the Buy Feature option gives you the chance of increasing your return to 98%.

The game takes place on a reinforced train being raided by armed bandits. While you start out with 5 reels, you can extend the reels by filling a reel with matching symbols.

You can trigger free spins by landing 3 bonus scatters in any position. However, 2 bonus symbols will earn you a free re-spin and a second chance of activating the feature.

During the free spins feature, the various characters can add modifiers to the game. You may earn additional random symbols, extra free spins, or bonus multipliers.

Money Train 2 is all-action and certainly not for the faint of heart. Play it at our best first deposit bonus casino in the UK.


Vikings Go Berzerk

Vikings go berzerk slot

RTP: 96.1%
Winlines: 25
Minimum Bet: 0.25
Maximum Bet: 125.00
Bonus Features? Yes
Jackpot? Yes

Vikings Go Berzerk is a beautiful 3D slot from leading developer, Yggdrasil Gaming. Its strong Viking theme is combined with amazing graphics and a range of top bonuses to satisfy all players.

The slot makes full use of its animated characters. When a Siren appears at random on the reels, a Viking will leap into action to defeat them. If he’s successful, a sticky wild is added to the reels.

And the more successful the Viking is, the quicker you’ll fill the rage meter. The Vikings launch into ‘berzerk mode’ once the meter is filled, meaning you’ll achieve a winning fight every time.

In addition, you can land treasure chests on the reels to trigger a cash prize or free spins. With a top payout worth £100,000, you’ll be itching to try Vikings Go Berzerk and earn a best online casino sign-up bonus.


Providers That Produce Slots With Bonus Features

Ready to get an online slots bonus in the UK? Here are some of the biggest providers offering bonus slots in 2021.



NetEnt is a Scandinavian software developer which provides casino games in the UK and around the world. NetEnt’s games are famous for their volatility and jackpots. They also produced the first cascading reels slot, Gonzo’s Quest.



Playtech is an industry leader in online casino slots and games. Many of the best bonus slots features like free spins, wilds, and progressive jackpots can be found in Playtech games.

Playtech boasts a portfolio of hundreds of online bonus slots, offering features like the free spins of Ocean Blue to the stacked wilds of Tiki Paradise, and the progressive jackpots of Age of the Gods.



UK casino giant, Microgaming, is one of the oldest slots developers on the planet. They released the first online slot in the 1990s and have produced 800+ games featuring an array of bonus features. Microgaming is also responsible for the record-breaking progressive slot, Mega Moolah, which has paid out tens of millions of pounds during its lifetime.



Wilds: Joker symbols that replace all regular icons in the game.

Walking Wilds: Special active wilds that move across the reels after each spin.

Multipliers: Symbols that guarantee an enhanced prize when they appear on the reels.

Scatters: Symbols that pay out regardless of where they land on the reels. Scatters also trigger an online slots free bonus.

Free Spins: A bonus feature where the player wins a set number of free games.

Re-Spins: A free spin awarded during the base game.

Cascading Reels: A feature where winning combinations are removed. Symbols then fall into the free spaces created.

Trail Bonus: A prize trail containing cash, free spins, or multipliers.

Pick ‘em Bonus: A second-screen bonus where players must choose from hidden symbols to reveal cash prizes.

Click Me Bonus: An instant win bonus usually featured during the base game. Choose from 3 hidden symbols to reveal a prize.

Progressive Jackpot: A linked jackpot made up of portions of qualifying bets.

Wheel of Fortune: A bonus feature where players must spin a wheel to win cash, free spins, or a jackpot.

Buy Feature: A feature that allows online slots bonus buys during a game. Pay a fixed cost and take a shortcut to the bonus feature.


Slots With Bonus Features FAQs

Look at our list of the top real money slots. Every game comes with a free spins bonus which can be triggered during the game.

Many top software developers offer games with a lot of the best bonus slots features. Games by NetEnt, Microgaming or Playtech offer a host of varied bonus games.

Of course! The best UK online casinos offer bonus slots which you can try with no risk. Just hit the Demo Play button and enjoy free slots with a bonus in your browser.

Potentially, you can win bigger jackpots with a bonus feature. However, bonuses also increase the volatility of the slot so you should be wary of downswings.

Yes! All our best bonus feature slots are licensed in the UK by the Gambling Commission. Enjoy safe and audited random number generators every time you play.



We collaborate with industry experts to make sure that our readers are getting the best possible content. All our articles are there to improve your casino experience.