Supplier Kambi will provide its sportsbook services to William Hill in the re-regulated Swedish market.
In March, the operator announced plans to enter Sweden but has since decided to accelerate this process.
William Hill will now rebrand its Redbet.se site to WilliamHill.se, with work "well underway" to align the Kambi sportsbook to meet this site's product requirements.
Kambi CEO Kristian Nylén recently told Gambling Insider the Swedish sports betting market is doing "very well" since having been re-regulated on 1 January.
Nylén said: "It’s a little bit tough for us to have a clear picture of it because we signed a very major customer in ATG. We expected this would be one of the top four Swedish sports betting brands early on.
"Obviously, that would have had some cannibalisation from existing customers, having other operators in the Swedish market. But, in total, I think the sports betting market is doing very, very well in Sweden. Our figures support that."