The former West Ham and Derby centre-back joined Palace in the summer of 2016, and went on to make 136 appearances for the club in all competitions over the course of eight seasons.
That total includes 30 appearances in the 2018/19 season, when Tomkins helped the club to equal its joint-best Premier League points tally.
The defender also scored 10 times for the club, most memorably on two separate occasions against Brighton at Selhurst Park, before departing at the end of 2023/24.