The 32-year-old all-rounder was responsible for arguably the most famous moment in T20 history when he smashed four consecutive sixes to win the 2016 World Cup for the West Indies at England’s expense.
Brathwaite, currently playing in the Pakistan Super League with Multan Sultans, has played in all premier T20 tournaments, the IPL, Big Bash and Caribbean Premier League.
He said: “It’s very exciting to join the Bears and to make Edgbaston my home this summer.
“I’ve heard a lot about the atmosphere and the big T20 crowds that come to Edgbaston to watch the Bears. I can’t wait to get started in the Blast.”
The Bears hope Brathwaite’s signing will help them improve after a succession of underwhelming campaigns in cricket’s shortest format.
“Carlos is an outstanding addition to our team,” said director of cricket Paul Farbrace.
“He’s a game changer who adds vital firepower to our middle order, but his variation with the ball also gives us another strong seam bowling option.”