Her most recent annual salary was £57m more than the previous year.
The company's overall revenue also increased by 7 per cent to £3.06b and pre-tax profit soared by a fifth to £791m.
According to the UK Guardian, Coates made the equivalent of A$2.48m ($2.5m) per working day in 2018 – a sum that is "9500 times the average UK salary".
However, Bet365 also donated A$190m to a slew of charities including Oxfam.
Who is Denise Coates?
Despite her unbelievable fortune, Coates is relatively unknown in the UK and around the world.
She lives a quiet life with husband Richard in Cheshire in northwest England and the couple's five children, four of which were adopted from the same family in 2014.
They are believed to live in a luxurious farmhouse, and Coates is known to drive an Aston Martin with personalised licence plates.
Coates, a former betting cashier who previously worked for her father's betting company, started Bet365 in 2001 in a temporary building in a carpark after graduating from Sheffield University with a degree in econometrics and buying the Bet365.com domain on eBay for £19,000.
She suspected online gambling would become the next big thing – and today, along with brother John and father Peter, the family has a multibillion-dollar fortune as a result.
But Coates' massive wealth has attracted its fair share of controversy.
Betting Backlash
The revelation of Coates' obscene pay has been slammed by members of the public, who have questioned the fairness of fat CEO salaries as everyday workers struggle to get by.
Social media users took to Twitter to attack Coates' pay, describing it as "pathetic" and "sickening".
The fact that Bet365's accounts were only revealed yesterday also caused some to question whether they were intentionally delayed until after the UK election, as failed candidate Jeremy Corbyn had vowed to crack down on the uber-wealthy if he took power.
Luke Hildyard, a prominent critic of excessive CEO pay in the UK, told The Guardian that Coates' salary was unfair.
"This looks like cynical timing, sneaked out straight after a general election campaign where excess wealth, taxes on the rich and the vast gap between those at the top and everybody else have been key issues," he told the publication.
"It's important that wealth and how it's created and shared are properly debated.
"But the publication of these figures seems designed to avoid scrutiny, suggesting that even Bet365 recognises that. While business success should be rewarded, such a colossal payout goes far beyond what is fair or proportionate."
Others also criticised the ethics of making billions from gambling, which causes addicts and their families significant suffering.
In a statement published by The Mirror, UK parents Charles and Liz Ritches, who were inspired to start anti-gambling charity Gambling With Lives following the suicide of their son Jack as a result of his gambling addiction, said Coates' pay was "upsetting".
"These companies know they are peddling addictive, potentially lethal products – as independent research confirms," the statement reads.
"Even (betting company) William Hill's website warns that gambling addicts are four times more likely to have suicidal thoughts than the rest of the population. This is beyond immoral."
