Gwyneth Paltrow's engagement party was a real who's who of Hollywood.
Shortly after returning from her bachelorette weekend in Cabo, Mexico, the 45-year-old Iron Man actress celebrated her engagement to fiancé Brad Falchuk on Saturday night with a black-scale event at the Los Angeles Theatre.
A source tells ET that the star-studded bash was thrown by Ryan Murphy, Falchuk's co-creator for hit shows like Glee, American Horror Story and Scream Queens. The party was for friends as the couple plans to have a more intimate, small wedding at a later date, the source adds.
Positively glowing after her recent tropical getaway, Paltrow arrived to her star-studded party wearing a flowing one-shoulder burgundy gown, which showcased her toned physique with a thigh-high slit and midriff cutout. Falchuk, 47, looked dashing in a traditional tuxedo paired with a white jacket.
The marquee on the Los Angeles Theatre adorably read "BF LOVES GP."
The festivities definitely featured the couple's A-list nearest and dearest dressed in their black-tie best. Many stars opted for all-black ensembles including Reese Witherspoon, Liv Tyler, Chelsea Handler and Jennifer Aniston, who was also wearing an arm brace. Julia Roberts was also spotted arriving to the bash with husband Danny Moder.
Prior to the event, Handler shared a boomerang of her party attire: a puff-sleeve black dress with strappy stilettos.
"Headed to my friend's engagement," she captioned the Instagram clip.
Actresses Cameron Diaz, Kate Hudson and Demi Moore opted for something brighter -- Diaz wore a red glittery ensemble and brought husband Benji Madden, while the Almost Famous actress attended alongside boyfriend Danny Fujikawa and covered her growing baby bump with a yellow ruffled gown. Moore also wore a head-turning red gown, and arrived with a date.
Paltrow's mother, Blythe Danner, was also snapped carrying a Monique Lhuillier garment bag.
Other famous guests at the bash included Paltrow's godfather, Steven Spielberg, as well as Rashida Jones, Rob Lowe, Matthew Morrison, Lake Bell and jewelry designer Jennifer Meyer.
Paltrow, who was previously married to Coldplay frontman Chris Martin, and Falchuk kept their engagement secret for more than a year, though the couple didn't acknowledge it until January.
For more on couple's wedding plans, watch the video below.