Manly forward Curtis Sironen will finish his five-year stint at the club at the end of the season after signing a two-year deal with English Super League powerhouse St Helens.
The 28-year-old second-rower, who was coming off contract, has played 130 NRL games, including 65 matches for the Sea Eagles since switching in 2017 from Wests Tigers, where he debuted in 2012 as an 18-year-old.
"I am very excited about the next chapter in my career and I couldn't have hoped to have signed with a better club," Sironen said in a St Helens statement.
"Every Australian player knows that the Saints set the benchmark in the Super League.
"It was a very easy decision for me because I always wanted to play in England at some stage and I feel now is the right time to be making the move."
He will join Bulldogs veteran Will Hopoate at Saints next year.
Manly CEO Stephen Humphreys said Sironen had given them great service and was a very popular player among his teammates.
"Curtis has been a fine player for our club. Curtis will continue to be an integral member of our squad as we head into the finals series," he said in a club statement on Friday.
Sironen wins the race to a Cherry-Evans kick
A four-time City Origin representative, Sironen's 2021 campaign has been limited to five games due to a serious knee injury suffered in round one.
He has been named on the extended bench for Saturday night's tussle with the Cowboys in Townsville.
After the Roosters beat the Raiders on Thursday night, the Sea Eagles need to beat the Cowboys to retain fourth spot and a second chance in the playoffs.