Myleene Klass went into labour shortly after co-hosting The One Show on BBC One on Wednesday.
The former Hear'Say singer gave birth to Ava Quinn with her fiance Graham Quinn was by her side.
Her spokeswoman said, "Myleene had a problem-free labour. Mother and baby are doing well."
Klass came second on I'm a Celebrity... Get Me Out Of Here last year.
The 29-year-old began her relationship with Quinn in 2001 when he worked as a bodyguard for Hear'Say reports BBC.