The four US, Russian and Japanese astronauts pulled up in their SpaceX capsule on Saturday after launching from NASA's Kennedy Space Center.
They will spend at least six months at the orbiting lab, swapping places with colleagues there since March.
SpaceX will bring those four back as early as Wednesday.
Moving in are NASA's Zena Cardman and Mike Fincke, Japan's Kimiya Yui and Russia's Oleg Platonov - each of whom were originally assigned to other missions.
"Hello, space station!" Fincke radioed as soon as the capsule docked high above the South Pacific.
Cardman and another astronaut were pulled from a SpaceX flight in 2024 to make room for NASA's two stuck astronauts, Boeing Starliner test pilots Butch Wilmore and Suni Williams, whose space station stay went from one week to more than nine months.
Fincke and Yui had been training for the next Starliner mission but with Starliner grounded by thruster and other problems until 2026, the two switched to SpaceX.
Platonov was bumped from the Soyuz launch line-up a couple of years ago because of an undisclosed illness.
Their arrival temporarily puts the space station population at 11.
The astronauts greeting them had cold drinks and hot food waiting for them.
"It was such an unbelievably beautiful sight to see the space station come into our view for the first time," Cardman said once on board.
While their taxi flight was speedy by US standards, the Russians hold the record for the fastest trip to the space station - a lightning-fast three hours.
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