Tomkins will now be with the club until the end of the 2021/2022 season, while Benteke has a contract that expires at the end of the 2020/2021 campaign.
While Tomkins is a key player, Benteke's renewal was a little surprising given he has only started two Premier League games and not scored a goal in league play this season.
Speaking about the renewals, Palace club chairman Steve Parish had the following to say: "I'm pleased that agreements have been reached with these two important senior players.
"Both James and Christian bring vast Premier League experience, commitment and professionalism to the squad.
"These new deals show that we recognise their levels of performance in recent seasons, that we believe in both players, and that they are hugely motivated by the direction the club is heading."