The 34-year-old actress, who attended the I-dos of her former costar on Friday, took to Twitter today to share two photos from the nuptials, and it's safe to say the blond beauty almost stole the spotlight in a sexy red dress.
"My bestie Chey and I perfecting our disenchanted fashionista pose before attending a wedding in upstate NY," the 27 Dresses star posted Monday on her social media page.
In the pic, Heigl looks radiant while showing off her slim figure in a fitted red gown that appears to have sexy cutouts on the side as poses with her best fashionista pout next to her pal. She wore her hair up in a delicate updo and added red handbag and chandelier earrings to her gorgeous ensemble, finishing off her flawless look with a bright red lip.
"Having the time of my life at said wedding with @katewalsh @joshbkelley Kate's amazing fella Chris & my girl Chey!," she wrote.
E! News confirmed Knight tied the knot with his longtime boyfriend Oct. 4 in a ceremony, which, according to Us Weekly, was "very small and quiet," although his former costar was clearly in attendance.
The newly married actor and The Ugly Truth actress previously starred together on Grey's Anatomy until T.R.'s departure in 2009, with Heigl leaving the show just one year later.
Coincidentally, Grey's star Ellen Pompeo, who is one of the original castmembers of the show, recently opened up to the New York Post about Heigl's controversial exit while chatting about the ABC hit's upcoming 200th episode.
"When Katie left, it was tough," she said of her former costar much-buzzed about departure after playing Dr. Izzie Stevens on the medical drama from 2005 to 2010. "You could understand why she wanted to go — when you're offered $12 million a movie and you're only 26. But Katie's problem is that she should not have renewed her contract. She re-upped, took a big raise and then tried to get off the show. And then her movie career did not take off."
Hey, at least she gained a few solid friends from her experience.