Kikai Sentai Zenkaiger (機界戦隊ゼンカイジャー, Kikai Sentai Zenkaijā, Mecha World Squadron Zenkaiger) is a Japanese tokusatsu television drama, the 45th entry in Toei's long-running Super Sentai series, and the second produced in the Reiwa era. Additionally, it commemorates the 45th anniversary of the Super Sentai franchise and is the second special anniversary series following Kaizoku Sentai Gokaiger.

The show succeeded Mashin Sentai Kiramager, joining Kamen Rider Saber, and later, Kamen Rider Revice in the Super Hero Time line-up on TV Asahi on March 7, 2021. The show's name comes from the titular team's catchphrase, "Zenryoku Zenkai" (全力全開, lit. "full throttle"). A direct sequel, titled Avataro Sentai Donbrothers, aired following the finale.Zenkaiger also aired in South Korea as Power Rangers Zenkaiger.