Flutter, owner of gaming brands Paddy Power, Betfair and FanDuel among others, will hold 54.64% of the new company, with Stars Group, owner of Sky Betting & Gaming, PokerStars and more, taking a 45.36% stake.
The deal is likely to be closely scrutinised by regulators as the merged firm, worth around £11bn in market capital, would hold a significant share in several markets, including the UK and US.
Flutter's current CEO Peter Jackson will be the new organisation’s CEO, with Stars Group CEO Rafi Ashkenazi becoming COO.
The company will keep the name of Flutter Entertainment and expects pre-tax cost synergies of £140m per year by the end of the third year post-merger.
As part of the deal, Fox Bet (part of Stars Group) will have the right to acquire 18.5% of FanDuel, while Fastball and Boyd Gaming will also receive 12.5% of the increase in Fox Bet’s market value under certain conditions.
Flutter’s share price rose around 18% to £89.80 on the morning of its announcement.