Collins made the announcement to Sports Illustrated and wrote a column that will appear in the Nov. 24 issue of the magazine.
Collins played 13 seasons in the NBA, eight with the Brooklyn Nets.
Collins went public about his sexuality in May of 2013, receiving both support and criticism from around the sporting world. His coach at the time, Jason Kidd, was a key voice in his corner.
Colllins says injuries and overall physical fatigue took its toll and it was time to step away from the game.
"My body was telling me it was time," he told SI.
Kidd now coaches the Milwaukee Bucks, the team that the Nets face on Wednesday at the Barclays Center. Collins says it means a lot that Kidd will be at the arena for his announcement.