Cousins, who is currently recovering from a torn Achilles injury, has agreed to a one-year deal worth $5.3million (£4m).
After undergoing surgery in January, Cousins became expendable and Pelicans brought in free-agent Julius Randle.
The Warriors, who lost their center JaVale McGee to the Los Angeles Lakers, will be the best place to help Cousins to continue his rehabilitation from injury.
Adrian Wojnarowski, an ever-reliable NBA insider, revealed the news on Twitter.
After the news broke, two-time league MVP Stephen Curry welcomed Cousins to the Warriors
