The Rolling Stones rocker - who already has seven children from previous relationships - will welcome his eighth child with 29-year-old ballerina Melanie Hamrick.
A spokesperson for Mick confirmed the news to The Sun while a source told the publication: "This is great news. It will be Mick's eighth child and nothing fazes him. He's been incredibly supportive.
"She's very bright, intelligent, sparky and has her own ideas about how she wants to lead her life. She knows what a great relationship Mick has with all of his children and can't wait for him to be a dad again.
"They are taking the news in their stride."
Mick and Melanie were first linked in 2014, when they were spotted canoodling on the balcony of his hotel in Zurich.
And earlier this year Mick - who has five grandchildren and recently became a great-grandfather - introduced the dancer to his kids, when she enjoyed a break with him at his holiday home on the private Caribbean island of Mustique.
However, she reportedly won't be moving to London to live with Mick when the baby is born, although sources say "he will love and support this child".
Instead she is believed to be planning to move to either Los Angeles, where he spends a great deal of time, or to Connecticut to be near her family.
In May, Mick's Rolling Stones bandmate Ronnie Wood, 69, welcomed twin daughters, Gracie Jane and Alice Rose, with his wife Sally, 38.
Update your news preferences and get the latest news delivered to your inbox.