The Welsh region announced a two-year deal for the Fiji international, who moved to Worcester from French club Racing Metro in 2012.
"I am really excited about this move," Matavesi, 23, said.
"The coaches want the team to play a good style of rugby, which is important to me.
"It is a young squad, particularly among the backs, but with plenty of games behind them. I've been around a fair bit myself now, despite being relatively young, and hopefully I can add something different."
Matavesi will leave Worcester at the end of this season.
- Sports & Recreation