The Serie A club have agreed to pay Chelsea a €3 million loan fee, with performance-related add-ons that could take the figure to €4 million, and will cover the France international's wages for the campaign. Napoli have the option to sign the 25-year-old permanently next summer for a further fee reported between €20 million and €27 million, depending on the outlet.
Badiashile joined Chelsea from Monaco in January 2023 in a deal reported at both £35 million and closer to €37-38 million across various sources, and has made 71 appearances in all competitions for the west London club since.
His time at Stamford Bridge was disrupted by injuries and inconsistent form, and he made just 16 appearances across all competitions during an injury-hit 2025-26 season, leaving him surplus to requirements under new manager Xabi Alonso.
The move is part of a broader trimming of Chelsea's central defensive options this summer, which has also seen Trevoh Chalobah agree a switch to Como worth up to €36 million, while Axel Disasi and Tosin Adarabioyo have also been linked with exits.
For Napoli, Badiashile becomes their second first-team addition of the window following the arrival of Costantino Favasuli from US Catanzaro, with the Serie A champions also confirming permanent deals for Rasmus Højlund, Alisson Santos and Vanja Milinković-Savić after triggering buy options on their existing loans.
Napoli president Aurelio De Laurentiis was quick to welcome the defender on social media following the announcement, posting "Benvenuto Benoît" shortly before the club's official statement.
Badiashile arrives in Italy with the club already underway in Serie A, having kicked off their title defence away at Genoa on the same day the move was confirmed.
For Chelsea, the departure continues a pattern of squad rationalisation under Xabi Alonso, who omitted Badiashile from the club's pre-season tour as talks over his exit progressed. The centre-back, capped at senior level by France, will hope a change of scenery in Naples can help him rebuild form and consistency after two difficult years in west London.