Morrow's agent, Wallace Prather, wrote in a text message to The Associated Press on Saturday that the deal is for three years and $10 million. The Thunder did not disclose terms of the deal Wednesday.
Morrow, who played for New Orleans last season, has career averages of 10.4 points and 2.5 rebounds per game in six NBA seasons. He helps fill a void created when starting shooting guard Thabo Sefolosha became a free agent and ended up with the Atlanta Hawks.
Morrow is a career 43 percent shooter from 3-point range, and similar production would be a major upgrade for the Thunder. He shot 45 percent from behind the arc for the Pelicans last season.