The 31-year-old Canadian, born Claire Elise Boucher, used a photoshopped image of a foetus to reveal that she was with child.
In response to a fan’s comment, she revealed that she is “knocked up”.
She didn’t say who the father was but Grimes has been in a relationship with Tesla billionaire Elon Musk since May 2018.
In response to another fan who said “omg queen of securing elon’s coin forreal #businesswoman”, Grimes responded “I don’t need $ from a man, Grimes is self-funded.”
Musk is already a father of five sons from his previous marriage to author Justine Wilson.
They were married between 2000-2008 but their relationship started to sour after the death of one of their sons from Sudden Infant Death Syndrome.
Musk then married actress Talulah Riley twice. They first divorced in 2012 after two years together but got back together and remarried before divorcing again in 2016.
He then dated actress Amber Heard between 2016 and 2017, with Heard’s ex-husband Johnny Depp accusing the Aquaman actress of cheating on him during their marriage with the billionaire.