The reality star, 27, shared the happy news on Instagram on Wednesday night, posting photos of her newborn son Theodore.
Frankie told her followers she and venture capitalist boyfriend Jamie Dickerson welcomed their baby boy on November 29.
Frankie shared a series of photos with the caption ‘Baby Theodore 29.11.21’, showing the newborn nestled on her chest after the birth.
Another shot saw baby Theodore wrapped up warm in a cosy jacket, sleeping soundly in a moses basket.
Frankie’s boyfriend Jamie featured in another sweet snap, cuddling his son as they both snoozed at home.
The star took to Instagram in July to announce she was expecting with her venture capitalist boyfriend.
Frankie first appeared on Made In Chelsea in its 11th season – and went on to star in the show until series 15, as well as the summer seasons in America, Ibiza and the South of France in between.
Her main story-line featured her rocky relationship with Jamie Laing, which came to an end at the end of 2017.
After her break up with Jamie, she attempted to get back into the dating game with current stars James Taylor and Harry Baron, but this went nowhere.
Last year, a source told The Sun that she was blissfully happy with her new businessman beau.
‘Frankie is smitten. She feels really comfortable with this Jamie and trusts him. He’s really mature and together, but they have a lot of fun too,’ the insider said.
Her last few appearances on MIC saw her lock horns with Olivia Bentley, who still stars in the reality show.
Rumours had rumbled about her quitting in 2018, before series 15 began airing.
When her final episode was shown, she confirmed the news by taking to Twitter and posting: ‘Ciao Ciao. Onto the next adventure!’
Her last scene saw her tell friend Sophie ‘Habbs’ Habboo that she needed time away from the drama and was last seen leaving Mimi Bouchard’s pyjama party.
Habbs has since gone on to form a romance with Jamie, and the pair have been together since. The state of Habbs and Frankie’s friendship is unclear.
Prior to her exit, it seemed that Frankie was losing her patience with the show anyway, tweeting during one episode: ‘Wow how boring are we, sitting in various cafes over London talking about boring boy bulls**t, as if that’s all there is to us!’