A former NRL star with Parramatta, Hayne shocked the rugby league world when he joined the NFL.
“I’d like to thank Jed and the entire York family for giving me the opportunity to fulfill my dream of playing in the National Football League,” Hayne said in a statement.
“The past 12 months with the San Francisco 49ers have been absolutely incredible. I could not have predicted how far I have come as an NFL player.
“To not only be able to play in a game but also say that I started a game in the NFL is something that I will remember for a lifetime.
“I am retiring from the NFL because the Fiji Rugby Sevens team reached out to me about the opportunity to join the team for the upcoming Olympics, and I simply could not pass that chance up.
“The Olympics has been something I have admired since I was a little boy, and it is an opportunity I feel very similar to me joining the NFL.
He originally signed with the 49ers as an undrafted free agent in March, 2015. Hayne appeared in eight games (one start) last season and registered 17 carries for 52 yards along with six receptions for 27 yards.
He also returned eight punts for 76 yards on special teams.