The 41-year-old funnyman confirmed he'd welcomed his first child with his fiancée, 27, Laura Gallacher, during a show in at the Nottingham Playhouse over the weekend.
"He didn't confirm if it was a boy or girl," attendee Daniel Crann told The Mirror.
"He was conscious of the clock and made sure he was off stage by just approaching 9pm as he 'needed to get down the f*ing M21 as my girlfriend has just had a baby,'" the punter added.
Although Rusty is yet to comment on the bub's gender, one well-wisher congratulated him on having a daughter.
"@rustyrockets I hear you have a baby girl. Many congratulations to you and Laura!! x," they penned.
Speaking recently to The Evening Standard, the star revealed he couldn't wait to become a dad.
"I feel lit up by the idea I'm very excited about becoming a dad and I'm preparing myself. I am just getting ready to be with a new little person and see what it is they want."
Former ladies' man Russ has been dating Laura, who works in hospitality, on and off for ten years. The couple split for the first time in 2007. Two years later they rekindled their romance, but failed to make their relationship go the distance.
But it seems that third times a charm for the new parents, who now share a $1.9 million Oxfordhsire home on the riverside after getting back together on a romantic weekend Rome last year.
According to The Sun, the recovering sex addict was allegedly “desperate to start a family” with his wife of two years, Katy Perry, before they split.
Now, four years on from their heartbreaking divorce, Russell is “blissfully happy” with his new leading lady.
Congratulations Russell and Laura, we can't wait to meet your bub!