The 74-year-old McCartney called the new contract, which encompasses his entire post-Beatles catalog, "genuinely exciting."
The record label said the music icon, who is still one of the biggest concert draws in the world, was "currently working on a new studio album," without offering further details.
"Paul McCartney's association with Capitol has long defined so much of our historic legacy, and all of us here are extremely proud and honored that he has chosen to come back home," said Capitol Music Group chairman and chief executive Steve Barnett.
"We are overjoyed that Paul will be creating new music for years to come, and that Capitol will be helping to present it to the world."
Capitol, which is part of Universal Music Group, said it was developing plans for how to manage McCartney's back catalog, and would implement them from next year.
McCartney, who has maintained a packed touring schedule in recent years, told Rolling Stone magazine in an interview published last week that he may need to slow down soon.
Asked if he could imagine touring in the same way at 80, McCartney replied: "Unimaginable and unseemly."
His latest global tour culminates in October at California's Desert Trip, a one-off mega-show that will also feature The Rolling Stones, Bob Dylan, The Who, Neil Young and Roger Waters.
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