Jay-Z says he cried with relief when his mum told him that she is gay.
"I was so happy for her that she was free," the rapper told David Letterman on his new Netflix show.
Jay-Z raps about the moment in the song Smile, on his latest album 4:44.
"Mama had four kids, but she's a lesbian/Had to pretend so long that she's a thespian. Had to hide in the closet, so she medicate/Society shame and the pain was too much to take."
Later in the track the 47-year-old says he's happy his mother has found love again.
"Imagine having lived your life for someone else. And you think you're protecting your kids," Jay-Z said on My Next Guest Needs No Introduction.
"For my mother to have to live as someone that she wasn't and hide and like, protect her kids — and didn't want to embarrass her kids... for all this time.
"For her to sit in front of me and tell me, 'I think I love someone'. I mean, I really cried."
The rapper says he'd known for a long time but only spoke to his mum about it eight months ago, when the album was being recorded.
"I knew. But this was the first time we had the conversation," Jay-Z said.
"And the first time I heard her say she loved her partner, like, 'I feel like I love somebody'. She said, 'I feel like'. She held that little bit back, still.
"She didn't say, 'I'm in love', she said, 'I feel like I love someone', and I just, I cried.
"I don't even believe in crying because you're happy. I don't even know what that is. What is that?"
The Jay-Z episode of My Next Guest Needs No Introduction starts streaming on Netflix on 6 April.