All three stars arrived at the popular event after their big wins, with Pitt taking home Best Supporting Actor while Phoenix won Best Actor and Zellweger came away with Best Actress.
Pitt, 56, was one of the first to make it from the bash, with partygoers cheering for his arrival. The actor was immediately swarmed with people congratulating him on his first acting Oscar. Among the first to approach him were Kim Kardashian West and Kanye West. The trio were seen laughing while catching up. Pitt is close with the couple, having frequented West’s Sunday Services in the past.
The actor was also approached by Once Upon a Time… in Hollywood costar Margaret Qualley and Geena Davis before making his way out less than an hour after he arrived.
Zellweger, 50, had a similar entrance, though she was one of the last attendees to walk through the door as her award was announced second-to-last during the ceremony. The actress was seen relaxing at the party after winning her second Oscar.
Phoenix, 45, opted to spend most of his time talking to newly-minted Grammy winner Billie Eilish. The two chatted outside the party for much of the evening after Phoenix arrived with fiancée Rooney Mara and his mom Arlyn.
West and Kardashian West also enjoyed themselves throughout the night, mostly sticking near her family members who were also in attendance. The couple was seen chatting with Kylie Jenner and Caitlyn Jenner, as well as family friend Nicky Hilton.
The rapper was wearing a big chain around his neck that was a Christmas gift from his wife, while she stunned in a dress West got her for Christmas.
The night also brought about a sweet Parks and Recreation reunion after Adam Scott, Rashida Jones and Nick Offerman all squeezed into a photo booth and were seen catching. Former The Office stars Mindy Kaling and B.J. Novak hung around with the group as well.
Those are just a few of the A-List stars who gathered at the party, click through the gallery above for some serious star power.