The actor is said to have attended her Christmas party last week, being one of the first to arrive and the last to leave the festive do.
They announced their split in January 2005 after five years of marriage, leaving fans devastated.
A source told E! News: “Brad arrived a little after 7 p.m. and most guests started arriving soon after.
“He was among the first arrive and the second to last guest to leave at close around 11 p.m.”
Also in attendance was Tom Hanks and his wife Rita Wilson and Kate Hudson and her partner Danny Fujikawa.
Jen’s former Friends co-star Lisa Kudrow and her current The Morning Show colleague Reese Witherspoon also joined in the fun.
The insider added: “It appeared to be a pretty low key casual affair, a gathering of close friends to celebrate the holidays.”
“The guests were all dressed comfortable and fairly casual.”
After they split Brad got together with Angelina Jolie, who he was married to from 2014 until 2016.
Jen married Justin Theroux in 2015 and they split in 2017.
When asked about her romantic life recently, she said she’s “open” to settling down with another man.
She told People: “Because it’s fantastic. It’s absolutely a beautiful thing. I mean I also think it’s the way we really get to know ourselves by being vulnerable enough to let love in.”
Jen, who found fame as Rachel Green on Friends, says her past relationships are what have upheld her belief in love.