The two stars, who dated from mid-2007 to late 2009, caught up at The Beverly Hilton Hotel amongst other big-name actors. An insider tells Us Weekly exclusively that Witherspoon, 38, and Gyllenhaal, 34, had a moment together during one of the show's commercial breaks.
"Reese paused and hugged Jake Gyllenhaal," the eyewitness tells Us. "They looked happy to see each other!"
The former lovers were both nominated for awards at the 2015 Golden Globes. Witherspoon was up for Best Actress in a Drama for her critically acclaimed role in the adaptation of Cheryl Strayed's Wild, but lost to Julianne Moore, who won the trophy for Still Alice.
Gyllenhaal was nominated for Best Actor in a Drama for Nightcrawler, falling to winner Eddie Redmayne, who was honored for The Theory of Everything.
Despite their losses, the friendly exes both looked stunning and happy at the star-studded event. Gyllenhaal looked sharp in a black tuxedo with a black bow tie, and attended on the arm of his sister Maggie Gyllenhaal, who won Best Actress in a Mini-Series or Film Made for Television for her role in The Honorable Woman.
With her inspiration Strayed by her side, Witherspoon went glam in a metallic beaded strapless Calvin Klein Collection dress. She accessorized the custom number with more than $1 million in Tiffany & Co. jewelry.
Now married to talent agent Jim Toth (they share son Tenneesee, 2), Witherspoon dated Gyllenhaal after her split from first husband Ryan Phillippe. The two stars got to know one another on the set of their 2007 drama Rendition. After their split, Gyllenhaal went on to date Taylor Swift in 2010, and model Alyssa Miller from 2013 to 2014.
"He's very supportive," Witherspoon told Vogue in November 2008 of Gyllenhaal. "Suffice it to say, I'm very happy in life, and I'm very lucky to have a lot of really supportive people around me who care very much for me, and, you know, that's all you can hope for in life. I am very blessed in that way."