Bet365 joint-CEO Denise Coates received £323m in compensation in the year to the end of March 2018, making her the UK’s highest paid executive.
Coates’ salary climbed to £277m according to the firm’s most recent accounts, up from £220m in the previous year.
She also earned tens of millions in dividends from the company she jointly owns with members of her direct family.
Her brother John serves as joint-CEO alongside her, while her father is chairman of the privately held gambling firm.
The total breaks the record for the highest-ever amount paid to an executive in a UK-based company. The £265m that Coates earned in the year to the end of March 2017 was the previous record.
The latest accounts, which were due to be filed on or around 20 November, were only published this week.
The bumper salary means that Coates, 52, effectively earned £1.3m for every working day in the firm’s financial year.
She is now the best-paid boss in the UK for the third year running, and Forbes magazine estimates her net worth to be in the region of $12bn (£9bn).
In January 2012, Coates was appointed a Commander of the Order of the British Empire by the Queen for her services to community and business.
Bet365 made before-tax profits of £791m, up from £661m in the previous year.
Her huge salary has prompted criticism from groups who argue that betting firms like Bet365 are not doing enough to counteract problem gambling and addiction in the sector.
While Coates runs the Denise Coates Foundation, which donates to charities such as Oxfam and the Douglas Macmillan Hospice, her pay package is more than the entire gambling industry donates to initiatives designed to combat the issue.
The House of Lords this year called for evidence on issues including a “lack of accurate estimates” of the scale of problem gambling. A committee said it wanted to understand possible links to suicides.