The singer, who hit the milestone on Sunday (12Jan14), thrilled the star-studded crowd at the Shepherd's Bush Empire with her Sporty's Forty gig, a nod to her former nickname, Sporty Spice.
Along with performing several solo hits, she duetted with her former bandmate Emma Bunton on the Spice Girls' song 2 Become 1, as well as singing Pure Shores with All Saints star Natalie Appleton.
She then tackled When You're Gone, which was originally a duet with Bryan Adams, but it was British DJ Chris Moyles, her co-star in rebooted stage musical Jesus Christ Superstar, who took the rocker's place on the night.
After the show, Chisholm tweeted: "Thank you to everybody for making my birthday so incredible. I had the best time ever!!!!"