The deals put Fitzgerald under contract through the 2017 season and Palmer through 2018.
Fitzgerald, holder of virtually all the franchise receiving records with statistics among the NFL's all-time greats, turns 33 on Aug. 31.
Palmer is 36 and entering his fourth season with the Cardinals. He set franchise records and personal bests for yards passing, touchdown passes and quarterback rating in leading Arizona to a 13-3 record last season.
Fitzgerald's 109 catches last season broke the franchise mark he set a decade earlier.
General manager Steve Keim said in a news release that the signings reaffirm the team's intention that "these two great players end their stellar careers with the Cardinals."