William Hill is to pay £424m sterling for full control of its online business, marking an acceleration of the expansion of Britain's largest bookmaker.
The deal to buy out the 29% stake in William Hill Online held by software company Playtech was the company's second major deal in the past three months.
It has already agreed to pay £460m for the Australian and Spanish operations of online gambling company Sportingbet, a deal set to complete on March 19.
The two transactions were designed to reshape William Hill, which was set up in 1934 and has more than 2,000 betting shops across the UK.
The company, which generates 90% of its revenue from Britain, wants to expand overseas and continue its strong growth in online where increasing numbers of customers now bet.
The online gambling sector is seeing a wave of consolidation. Ladbrokes, Britain's second-largest bookmaker, completed the €30m buyout of Dermot Desmond controlled betting exchange Betdaq today after a number of failed takeover talks with larger companies.
William Hill's chief executive Ralph Topping, who has worked for the bookmaker for 40 years, said: "This move rounds off a successful 12 months which have seen us take our first steps into the US and, through the pending Sportingbet acquisition, lay the foundations for growth in the attractive Australian market".
William Hill triggered an option to buy the stake held by Playtech since the venture was set up in 2008. The price was broadly in line with forecasts.
Topping said it had been agreed after bankers for both sides submitted valuations, without needing to call in a third party.
William Hill bought three businesses in the US state of Nevada last year and Topping said he was encouraged by news this week that New Jersey had legalised online gambling.
He also said it was wrong to write off traditional land-based betting despite the fast growth of online. "Any company that goes with one view of the world risks missing an opportunity."