Martinez, who joined Villa in 2020 and made 256 appearances, helping the club win the Europa League last season, has expressed his delight at joining Chelsea. "I'm delighted to be at this football club," he said. "Coming to Chelsea, for me and my family, was an easy decision to make and I'm just over the moon - I can't wait to get started."
The move comes after Nicolas Jackson's transfer to Villa the other way last week, and marks the latest in a series of deals between the two clubs. Since 2022, Chelsea have paid Aston Villa £163.5m for players, while Villa have spent £102.5m on Chelsea players, including Axel Disasi's loan fee.
Martinez's move to Chelsea is set to be followed by a potential permanent deal for Alejandro Garnacho, who joined Villa on loan with a conditional obligation to buy in a deal worth around £43m.