The 54-year-old actor attended the Gersh Oscar Party at Chateau Marmont in Los Angeles, California, and was joined by his manager, Cynthia Pett-Dante.
Pitt seemed in good spirits as he posed for a photo wearing an all-black winter ensemble that included a trendy hat. He's also sporting a bit of salt-and-pepper stubble these days.
“[Brad] was pretty low-key, but in a good way,” an eyewitness tells ET. “He was in a happy mood. He did not stay long, but while inside he spent time speaking with friends.”
Also at the party were I, Tonya co-stars Margot Robbie and Allison Janney as well as Three Billboards Outside Ebbing, Missouri actor Sam Rockwell and The Shape of Water's Richard Jenkins. In addition to these Oscar nominees, Angela Bassett, Tiffany Haddish, Elizabeth Olsen, Kathryn Hahn, Rockwell's longtime girlfriend, Leslie Bibb, and Stranger Things star Joe Keery were in attendance.
ET’s eyewitness says Robbie and Janney “were in great spirits” at the event and were enjoying glasses of Perrier-Jouët Belle Epoque champagne.
Brad Pitt and Jennifer Aniston Are 'Not Together' But 'You Can't Predict the Future,' Source Says
“They have each other’s cell phone numbers and communicate from time to time. [However], this is nothing new. Jen and him [Brad] have remained friendly," says the source, noting that Pitt and Aniston have stayed in touch since their split in 2005.
That being said, a source did tell ET in January that Pitt has gone on several "casual dates" since his split from wife Angelina Jolie in September 2016, but "none of them have evolved into anything serious."