The bookmaker launched a review its advertising account earlier this year, following the departure of chief marketer Jonathan Devitt.
Leo Burnett defeated four agencies to win the business, although previous incumbent Lucky Generals opted not to pitch. The review was handled in-house.
The agency has been briefed to relaunch the brand with an overarching idea and multi-channel campaign, breaking in the summer, to position Betfair as a destination for sports bettors.
Betfair’s UK and Ireland brand director Stephen Mault said: "We went to pitch with a customer-led brief and were really excited by the work Leo Burnett presented. We look forward to launching a new Betfair brand proposition in 2018 and bringing it to life across all our key territories."
Lucky Generals won Betfair in 2016 after the betting brand merged with Paddy Power earlier in the year. Its first campaign for the brand took a more serious tone to gambling advertising compared to its typically humorous spots for Paddy Power.
Paddy Power Betfair hired a new chief executive last year, bringing in Peter Jackson to replace Breon Corcoran.
Gareth Collins, chief executive of Leo Burnett, added: "We are delighted to embark on our new partnership with Betfair, one of the genuine innovators of the industry and we look forward to doing great work together."