The singer performed a number of his hit tracks from the last 20 years at the O2's Shepherd's Bush Empire in London in front of his celebrity pals.
Guests such as Kimberley Walsh, David Walliams, Lulu as well as his Take That bandmates joined him to celebrate his birthday.
Barlow also duetted with Coldplay's Chris Martin as well as British singer Ellie Goulding.
His Take That pals - Mark Owen, Howard Donald and Jason Orange - all joined him on stage for a sing-a-long while Robbie Williams was absent as he was in LA but sent a video message to wish him well.