Oscar Thomas will leave the club at the end of the season having agreed to join Bradford Bulls in 2016.
Thomas made his first team debut last season having rejoined the club after a spell in rugby union at London Irish.
Head coach Andrew Henderson said: “We’re disappointed to lose Oscar, we offered him an improved deal to stay with the club but he’s decided to go elsewhere.
“I’ve enjoyed working with Oscar and seeing him progress his development. We wish him the very best, hes going to a good club with good coaching staff and hopefully he’ll establish himself and perform consistently, I just hope he doesn’t do it against us.
Oscar Thomas says he is grateful for the Broncos giving him the opportunity to rejoin the club last season.
“I’d like to thank the club for giving me the opportunities I’ve had since I rejoined last season. I’ve made some good friends here and I will always look out for the Broncos in the future.”