Jason Collins, a 34-year-old who most recently played for the Washington Wizards, came out in an article with Sports Illustrated magazine.
“I’m a 34-year-old NBA centre. I’m black. And I’m gay,” Collins wrote. “I didn’t set out to be the first openly gay athlete playing in a major American team sport. But since I am, I’m happy to start the conversation.
“I wish I wasn’t the kid in the classroom raising his hand and saying, ‘I’m different.’ If I had my way, someone else would have already done this. Nobody has, which is why I’m raising my hand.”
‘Years of misery’
Collins said he was pleased he could “stop hiding” and that living a lie had meant enduring “years of misery”.
He wrote: “No one wants to live in fear. I’ve always been scared of saying the wrong thing. I don’t sleep well. I never have. But each time I tell another person, I feel stronger and sleep a little more soundly.
“It takes an enormous amount of energy to guard such a big secret. I’ve endured years of misery and gone to enormous lengths to live a lie. I was certain that my world would fall apart if anyone knew.
“And yet when I acknowledged my sexuality I felt whole for the first time. I still had the same sense of humour, I still had the same mannerisms and my friends still had my back.
He added: “Pro basketball is a family. And pretty much every family I know has a brother, sister or cousin who’s gay. In the brotherhood of the NBA, I just happen to be the one who’s out.”
Collins, who is now a free agent, has reached the NBA finals twice and said he intended to continue his career.
Basketball players in the States have come out before, but only after they have retired. In 2007 British basketball player John Amaechi, who played in the NBA, came out.
Other prominent British sports personalities who are gay or bisexual include former professional rugby player Gareth Thomas, Olympic boxing gold medallist Nicola Adams, and Paralympic equestrian Lee Pearson.