The 19-year-old winger joins Palace after impressing in appearances off the bench for the Under-21s against Manchester United – a match in which he scored – and Reading.
Mathurin started his footballing journey at Chelsea’s Academy at the age of nine, before making the switch to north London to join Tottenham Hotspur Under-13s.
The winger progressed through the ranks to feature up to U18 Premier League level, playing four times in last season’s UEFA Youth League. He also featured for the Tottenham first-team during their mid-season friendly against Peterborough United.
After putting pen-to-paper on his deal, Mathurin said: “This is a great opportunity at Crystal Palace. I’m happy to be here and I can't wait to progress.”
Academy Director Gary Issott added: “After a successful trial period, we are pleased to offer Roshaun the opportunity to join our Under-21s group.
“Supporters may have seen his impact in our recent home win over Manchester United, where he came off the bench to put in an exciting attacking performance for the team, and we hope that success will continue.”