Rins, a six-time MotoGP race winner, joined Yamaha from LCR Honda for the 2024 season, and will continue to race alongside Fabio Quartararo, who also extended his contract until 2026 earlier this year.
"Alex is not only a very talented and fast rider, but he is also technically savvy, a hard worker, and a real team player," Lin Jarvis, Yamaha managing director, said.
"The collaboration between Alex and Fabio gives Yamaha the confidence that together they can strengthen the bike development project."
Rins recently underwent surgery on his wrist and ankle after a crash at the Dutch GP, but will return to action at the British GP this weekend.