Weighing in at 6lb 10oz, Petal is the third girl for former model Jools and celebrity chef Jamie, who are also parents to Poppy Honey, 7, and Daisy Boo, 5.
Petal was born 3 days late-and it's a good job as on Wednesday, her due date, dad Jamie was at Number 10 cooking for Barack Obama's visit!
Jamie's now looking forward to 2 weeks paternity leave with Jools and his three girls. Announcing the birth, the couple's spokesman said: "Jamie and Jools are both completely smitten with Petal already."