According to the pics and videos posted on Alba's Snapchat story, the theme of the night was Prince vs. Michael Jackson, and it appears almost all of her guests had fun dressing in their best '90s gear.
The birthday girl put her own sexy take on the theme, sporting a sheer jacket over a strapless, cleavage-baring jumpsuit, which she paired with fingerless lace gloves, statement jewelry and heavy purple eye makeup.
There were plenty of treats for the guests inside the party, including a colorful macaroon cake, which featured Alba's picture.
Celebrity hairstylist Jen Atkin documented the moment the massive cake was brought out to Alba, as the crowd sang "Happy Birthday," and shouted, "We love you!"
An eyewitness tells ET Alba and about ten of her closest friends kicked off the night with dinner at Delilah, then headed over to the Peppermint Club for the official fête. Her party guests included Beyoncé, Kelly Rowland, Jaime King, Shay Mitchell, will.i.am, Nicole Richie, Cameron Diaz, Benji Madden, Joel Madden, Harold Perrineau, Rebecca Gayheart and Russell Simmons.
Alba's husband, Cash Warren, was also in attendance, rocking a glitzy cheetah-print blazer and black hat.
Ahead of the bash, he took to Instagram to gush over his gorgeous gal.
"I've spent the last few days wondering what to say to you on your birthday and I've come to the realization that words aren't enough," he wrote. "Words can't describe the feelings I had when we first met. They can't describe the thoughts that went through my head when you said 'yes.' They can't describe my emotions when our daughters were born."
"They can't describe the warmth in my heart when we hug," he continued. "They can't describe the joy when you make me laugh. They can't describe how strong I feel when you hold my hand. They can't describe how much I love loving you. Thank you for giving me a lifetime of experiences that I can't describe with words. Happy Birthday my babe!!"