*NSYNC's Lance Bass Celebrates 40th Birthday With Boy Band Buddies and Spice Girls Music -- Pics

Lance Bass
Jerritt Clark/Stoli Vodka

The singer celebrated the milestone with his famous friends including Lisa Vanderpump and several of his fellow boy banders.

Lance Bass has officially joined the 40 club!

The *NSYNC heartthrob celebrated the milestone with a star-studded “May the 40th Be With You” bash at his new restaurant, Rocco’s WeHo, in West Hollywood, California, on Saturday.

Wearing a colorful sweater and drinking out of a gold Moet vessel, the singer was joined by husband Michael Turchin, current boy band tourmates O-Town and Ryan Cabrera, longtime pal Lisa Vanderpump, 98 Degrees singer Jeff Timmons and *NSYNC bandmate JC Chasez, who also rocked bright colors via a floral jacket and orange baseball cap.

Guests danced the night away to a '90s cover band, with O-Town singer Jacob Underwood’s fiancée, singer Chandler Bay, posting an Instagram Story showing the dance floor going off to the Spice Girls' hit, “Wannabe.”

“The room was singing '90s hits the top of our lungs and with a packed dance floor. So much fun!” a partygoer told ET.

Bass was presented with a three-tiered birthday cake by Lady M Cake Boutique, while guests made a champagne toast with Moet and were served finger food. “I always found Jeff from 98 Degrees by the salad all night. No wonder he stays so fit!” the guest said.

Themed birthday cocktails were also served, like the *NSYNCO de Mayo which was made from Stoli Cucumber, pineapple, jalapeno and lime.

“Best. Birthday. EVER!!!” Bass captioned a series of photos on his Instagram account on Sunday. “@roccosweho was on ? with some of my favorite people on Earth! My friends know how to throw one hell of a party. Thank you! ❤️ ?:@guapcityproductions #MayThe40thBeWithYou."

The fun photos showed Bass chilling with Chasez, posing with actress and bestie Jamie-Lynn Sigler and cozying up to another BFF, Real Housewives of Beverly Hills star Vanderpump, who was sparkling in dazzling head jewels.

O-Town members Underwood, Trevor Penick and Erik-Michael Estrada also posted snaps from the bash. O-Town and Cabrera are currently part of the Pop 2000 Tour, which Bass hosts.

As for Bass’ other bandmate, Joey Fatone, he wasn't able to attend as he was at the Kentucky Derby, where he hit the stage to perform covers with Backstreet Boys members Howie Dorough and Kevin Richardson at the Barnstable Brown Gala on the eve of the big race. Fatone’s girlfriend, Izabel Araujo, sent him photos from the party.

Forty could be the beginning of a whole new chapter for Bass, who has been working on starting a family with Turchin via surrogacy.

Last June, the singer opened up to ET about his plans to be a father by this summer.

“It’s looking like this might be the last Father’s Day that I’m kid-less!” he shared. “We’ll see if the timing’s right. We’re hoping to have a kid next summer, so we’ll just see how everything works out. Who knows what wrenches might be thrown in, so we’re just crossing our fingers that it all works out.”

“Our surrogate fell into our laps through our embryologist, who is incredible,” he added. “She was so selfless and all about wanting to give that gift to someone. I wanted to cry because it was just so special that someone would do that.”

See more party pics below.

Jerritt Clark/Stoli Vodka
Jerritt Clark/Stoli Vodka
Lance Bass