David and Victoria Beckham arranged for the boyband to appear at the party on Saturday (September 1), reports The Sun.
A source said: "Victoria has some handy connections with the band and it wasn't hard to get them along.
"They met all Romeo's pals and posed for snaps. It's the easiest gig they've ever had."
Victoria later thanked the band on Twitter, stating: "The @thewantedmusic boys, the coolest boys in music!!! Thank you for making Romeo's 10th birthday so special!!!! X vb."
Romeo also celebrated his birthday by appearing as his father's team LA Galaxy's mascot for their 2-0 win over Vancouver Whitecaps. The game saw David Beckham score a free kick.
Victoria has previously praised The Wanted, telling Glamour: "I have a soft spot for The Wanted - they're a great British export and such nice guys.
"They taught my son Brooklyn to play guitar!"
The Wanted recently teased that their upcoming collaboration with LMFAO will be "insane".