The company was founded by William Hill in 1934. It changed hands many times, being acquired by Sears Holdings in 1971, then by Grand Metropolitan in 1988, then by Brent Walker in 1989. In September 1996, Brent Walker recouped £117m of the £685m it had paid for William Hill when Grand Metropolitan was found to have exaggerated the company’s profits at the time of the sale.

Japanese investment bank Nomura mounted a £700m leveraged buyout of William Hill in 1997 when Brent Walker collapsed with debts exceeding £1.3bn after an investigation by the Serious Fraud Office which saw two directors given prison sentences. In February 1999, a proposed stock market flotation was abandoned due to “weak interest” and Nomura offloaded the company to funds managed by private equity firms Cinven and CVC Capital Partners for £825m instead.

The company was eventually listed on the London Stock Exchange in 2002. The following year Chief Executive David Harding was awarded a £2.84m bonus, making him the UK’s fifth highest-paid company director in 2003. It acquired Sunderland Greyhound Stadium in 2002 and Newcastle Greyhound Stadium in 2003. In June 2004, Chief Executive David Harding sold £5.2m of shares to fund his divorce, precipitating a decline in the company’s stock that wiped £75m off the value of the company. In 2005, William Hill bought 624 betting offices in the UK, the Republic of Ireland, Isle of Man and Jersey from Stanley Leisure for £504 million: the acquisition briefly took the company past Ladbrokes into the first position in the UK betting market in terms of shops but not revenue. The Office of Fair Trading made William Hill sell 78 of the 624 Stanley shops due to concerns over anti-competitive practices.

Amidst fears that William Hill had overpaid for the Stanley shops, the company was relegated from the FTSE 100 Index in December 2005. In 2008, Ralph Topping was appointed Chief Executive. After having dropped out of Strathclyde University as a self-confessed ‘rascal’, Topping had taken a Saturday job at a William Hill betting shop near Hampden Park, Glasgow, in 1973 and worked his way up through the ranks. In November 2008, William Hill went into partnership with Orbis (latterly OpenBet), an Israeli software company Playtech, to remedy its own failing online operation.

In November 2008, analysts at UBS noted “concern” at the company’s level of debt, which stood at over £1bn and was later reported as £1.5bn. In 2009 the company enacted both a rights issue and a corporate bond issue, in an effort to restructure its debt.

Under the terms of the deal, William Hill paid Playtech’s founder Teddy Sagi £144.5m for various assets and affiliate companies. These included several online casino sites which William Hill continues to run under the name WHG. Playtech took a 29% stake in the new William Hill Online entity. The company wrote off a reported £26m when scrapping their previous in-house system. In June 2009 William Hill backed Playtech despite their partner having a quarter of its stock market value wiped out following a profits warning.

In 2013, William Hill paid £424 million ($643 million) for full control of its online business marking an accelerated expansion and resulted in the dissolution of the partnership with Playtech.

On 7 January 2019, William Hill received regulatory approval to conclude its purchase of Mr Green for £242 million.

On 17 July 2020, William Hill raised £224 million in a new ordinary share rights issue to provide a timely capital boost during the COVID-19 pandemic. In August 2020, as a result of the economic effects caused by the COVID-19 pandemic, the company announced that it would close 119 shops permanently. Despite that, only 16 employees would lose their job positions, while the others would be assigned to new positions. It also announced that the firm would be merging its retail and online operations.

On 30 September 2020, William Hill agreed to a £2.9 billion takeover bid by Caesars Entertainment, the Nevada-based casino operator. The deal was unanimously recommended by the UK company’s directors. It came after two rival bids by the US private equity group Apollo were turned down. In April 2021, Caesars completed its acquisition of William Hill. On 22 April 2021, William Hill was delisted from the London Stock Exchange.

On 9 September 2021, William Hill International was acquired by 888casino from US owners Caesars Entertainment for a purchase price of £2.2 billion.