The 37-year-old actress and 39-year-old actor ran into each other Tuesday at John F. Kennedy International Airport, according to an Instagram post from Bilson.
Bilson shared a goofy selfie with Brody from the airport. She referenced The O.C. theme song "California" by Phantom Planet in the caption.
"Ran into my ol buddy from jfk to lax #californiaherewecome," she wrote.
The O.C. creator Josh Schwartz jokingly responded in the comments.
"Sorry don't get the reference," the producer wrote.
Bilson and Brody played Summer Roberts and Seth Cohen, respectively, on The O.C., which had a four-season run on Fox from 2003 to 2007. Bilson told Entertainment Tonight in June 2018 that no plans exist for an official reunion.
"I mean, I would do it," she said. "I'll tell you about three people that wouldn't do it -- five people? Six people? Eight people, let's be honest."
Bilson said her time on The O.C. was a "pretty crazy" experience.
"I guess I didn't really know what to expect," she said. "I think we kind of felt like, 'Oh, this could be a special thing.' It was a weird time, but it was a lot of fun."
Bilson will star in the new Fox pilot Lovestruck. She is parent to 4-year-old daughter Briar Rose with her ex-partner, actor Hayden Christensen, and discussed dating as a single mom in an interview in July.
Brody plays Nick Talman on the Crackle series StartUp, and will appear in the new film Ready or Not, which opens in theaters Aug. 21.