Rocket won the business after a competitive pitch and is expected to invest in TV as Betsafe plans a "highly ambitious" strategy to break into the UK’s online betting and casino sector.
Betsson Group, the Swedish-based owner of Betsafe, has not previously had a media agency but has had advertising partnerships with Manchester City and Gumball 3000.
Neill Simpson, UK brand manager of Betsson Group, said: "Rocket demonstrated an inherent understanding of the Betsafe ‘No Bullshit Betting’ brand positioning and we’re delighted to be working with them for a series of high-profile communication initiatives across 2016."
Nick Walker, Rocket’s chief client officer, will lead the account.
Win Cash Live, another gaming rival, appointed Arena Media in another seven-figure deal last month.