The 21-year-old will join his Knights teammates at training on Monday to bolster a backline that has lost Shaun Kenny-Dowall and Jesse Ramien for 2020.

The deal locks him in for the Knights until the end of 2021, with an option in his favour to stay on in 2022.

New coach O'Brien said the Queensland under-20s and Junior Kangaroos representative will add starch to the backline.

"He has NRL experience and is a strong defender. We need to be a resilient, strong defensive club. He's a big and powerful centre," O'Brien said.

"He adds the needed depth to our outside backs with Shaun Kenny-Dowall and Jesse Ramien leaving. He's competitive and looks to have a tough mindset."

He joins former Broncos centre Tautau Moga, Hymel Hunt and Bradman Best in contention for starting centre positions next year.

Shibasaki made his NRL debut under Wayne Bennett at the Broncos in 2018, and played 12 games for the club last season.

His release frees up space for halfback Brodie Croft to join the top 30 squad.

"Gehamat has been with the Broncos since his early teens and it was a proud moment when he made his debut for the club last year in Townsville, the town where he grew up," said Broncos CEO Paul White.

Australian Associated Press