The Canadian singer – who split up with the Tesla founder in September 2021, but has since reconciled with him – was pushed to reveal the news during a recent interview with Vanity Fair, when a baby was heard crying upstairs.
She told the magazine that she and Elon had welcomed a daughter via a surrogate in December 2021, shortly after their split.
“I don’t know what I was thinking,” she said of their decision not to tell the world their baby news.
The pair were already parents to an almost two-year-old son, X Æ A-Xii, and while Grimes chose not to reveal her daughter’s name to Vanity Fair, she did share that they call her Y.
Explaining where things stand with Y’s father, Grimes said: “I would probably refer to him as my boyfriend, but we’re very fluid. We live in separate houses. We’re best friends. We see each other all the time [...] We just have our own thing going on, and I don’t expect other people to understand it.”
“This is the best it’s ever been,” she continued. “We just need to be free.”
Grimes – whose legal name is Claire Elise Boucher – added that she and Elon may have more children in the future, stating they’d both “always wanted at least three or four”.
The couple were first reported to be dating in May 2018, and made their first public appearance together at the Met Gala that same month.
Grimes gave birth to a son in 2020, later clarifying his unusual name referred to “the unknown variable”, artificial intelligence and the couple’s favourite aircraft.
The 50-year-old entrepreneur has had six children from previous relationships, one of whom died as a baby. He has been married three times, including twice to Westworld star Talulah Riley.