Former England Under-21 international Wickham arrived at Selhurst Park in 2015 from Sunderland but injuries have reduced him to just 35 Premier League appearances during his four seasons at the club.
The 26-year-old sustained a serious knee injury in November 2016, keeping him out of first-team action until October 2018, and he did not start a game until January 2019.
Despite the injury issues, Palace have kept faith with the striker, handing him a two-year extension, and Wickham says he is grateful to be given the opportunity to keep playing for the club.
"I'm pleased to have got everything sorted, so I can now fully focus on working my way back into the team during pre-season and the upcoming campaign. I hope I'll be able to show that when fully fit I'm capable of playing a key part," he told the club's official website.
"It meant a lot that the club backed me after such a serious injury and I hope I'll be able to repay that faith shown in me."