The Black Cats have confirmed the free transfer signings of Cabral as well as Valentin Roberge and Modibo Diakite as manager Paolo Di Canio re-shapes his squad
The trio have each signed three-year contracts and now join the Black Cats for pre-season training alongside fellow summer signing, 19-year-old attacker David Moberg Karlsson from IFK Goteborg.
Paolo Di Canio began the move to bring in Roberge when his contract at Maritimo expired before the end of the season, and the Paris-born centre-back can also play on the left of the defence.
Fellow centre-back Diakite, also 26 and born in Paris, spent seven seasons with Lazio, during which he won the Coppa Italia in 2008-09.
Cabral won his fourth consecutive Swiss league title and reached the Europa League semi-final against Chelsea last year with Basel. He has appeared for the Switzerland Under-21 side, but made his international debut for Cape Verde in November 2012.