Jennifer Aniston and Justin Theroux finally tied the knot!

The couple managed to pull off a rare feat by marrying in a private ceremony Wednesday night, in an event that nobody knew was coming.

According USA Today, around 70 guests arrived to celebrate the nuptials, although they thought they were there for a birthday party - Justin is turning 44 on Monday, August 10.

A source for People Magazine said that the ceremony was held inside Justin and Jen's Bel Air mansion.

Although guests started arriving around 4:30 in the afternoon, Jen did not go outside until around 9PM, when the music and festivities were going strong.

The shindig, which a US Weekly insider said to feel more like a "warm house party" than an over-the-top event, was intimate and celebrated only with their closest friends, including Courtney Cox, Lisa Kudrow, Howard Stern, Chelsea Handler, Emily Blunt, John Krasinski, Ellen Degeneres, Lake Bell, and Scott Campbell, among others.

The party was said to have a lot of food and dancing, and a giant vanilla and strawberry cake topped with a pair of puppets.

The couple and their friends were serenaded with a private concert by Sia, who performed several songs, including her hit, "Chandelier."

People Magazine pointed that in hindsight, her involvement in Jen's wedding would have been apparent as she was seen having dinner with Jen and BFF Cox in May.

The day was memorialized in photos shot by the couple's close friend, Terry Richardson. The couple also had longtime friend Jennifer Meyer to thank for their beautifully designed wedding bands.

As for their honeymoon, a source for People said that the couple took a private jet to Bora Bora with a few pals invited along to keep the party going.

Aniston and Theroux, have always been in the same circles - they met via mutual friend Ven Stiller. According to E! News, they didn't start dating until 2010, when they starred together on the set of "Wanderlust".

The couple had been engaged since 2012 but have been secretive about their wedding plans as they kept friends and paparazzi on the hook with nothing but wild guesses. After all, long engagements are not really a Hollywood thing.

However, it seems that Jen really wanted it to be just right. She told the Associated Press in 2013, "We just want to do it when it's perfect, and we're not rushed, and no one is rushing from a job or rushing to a job. And, you know, we already feel married."