Apple CEO Tim Cook on Thursday said in an op-ed in BloombergBusinessweek that "I'm proud to be gay," addressing rumors about his sexual orientation.

"While I have never denied my sexuality, I haven't publicly acknowledged it either, until now," he said in his commentary. "So let me be clear: I'm proud to be gay, and I consider being gay among the greatest gifts God has given me."

Read MoreCNBC's Next List: Apple's Tim Cook



He noted that being gay has provided a window into the challenges that people in other minority groups deal with every day.



"I don't consider myself an activist, but I realize how much I've benefited from the sacrifice of others," he wrote. "So if hearing that the CEO of Apple is gay can help someone struggling to come to terms with who he or she is, or bring comfort to anyone who feels alone, or inspire people to insist on their equality, then it's worth the trade-off with my own privacy."

Apple chairman Art Levinson responded to Cook's essay, calling him "courageous."

Read MoreTImCook's coming out is historic: Openly gay CEO

"[Cook's] decision to speak out will help advance the cause of equality and inclusion far beyond the business world. On behalf of the board and our entire company, we are incredibly proud to have Tim leading Apple," Levinson said in a statement.

Read Cook's full commentary here.