The Hollerback Girl singer enjoyed a meal at exclusive Italian restaurant Cecconi's in West Hollywood on Saturday (10.10.09), where she was joined by husband Gavin Rossdale and their two sons, Kingston, three, and 13-month-old Zuma.
Some of Gwen's close friends, including Kate Beckinsale and her husband Len Wiseman, were also invited and guests celebrated the occasion in the restaurant's private Butterfly Room, which features a $1 million heart shaped Damien Hirst painting and a crystal chandelier.
An onlooker told People magazine: "The Butterfly Room was specially decorated for Gwen's celebration with happy birthday balloons and roses.
"Gwen looked amazing and so much younger than 40. She was in a great mood and seemed very excited to celebrate her birthday with her husband, children and friends. Gwen and Kate seem very close and the girls shared a long chat and many laughs. Gavin and a nanny took care of the boys so Gwen could just relax and enjoy her celebration."
After the meal, Gwen who reached the landmark age on October 3 -was helped by Kingston when she blew out the candles on her birthday cake.
The night before (09.10.09), Gwen and Gavin and spent a night with friends as they celebrated her birthday without the children.
A source said: "Gwen and Gavin spent a great night with friends and looked very happy together. When the clock struck midnight, Gwen and Gavin toasted to Gwen's big birthday."
