The 40-year-old actress wished Prinze a happy 42nd birthday in a joking message Thursday on Instagram.
Gellar shared a photo of herself and Prinze posing cheek to cheek. The couple married in 2002, and have two children, 8-year-old daughter Charlotte Grace and 5-year-old son Rocky James.
"Gorgeous, friendly, sexy, sweet, intelligent, super talented, kind, charming, funny, witty, amazing smile....well that's enough about me.... #happybirthday @realfreddieprinze (you're pretty great too)," Gellar captioned the picture.
Gellar and Prinze celebrated their 15-year wedding anniversary in September. Prinze shared the secrets behind their long-lasting marriage in an interview with Us Weekly published the same month.
"We treat each other with respect, we didn't just get married because we thought the other was young and hot. I think that sort of crushes relationships a lot," the actor said.
"Sacrifice is something that's required in marriage. It's fun being single, right? You can be selfish," he added. "But marriages require a step back from that and a bit of sacrifice, and our sacrifice I think is maybe the biggest thing that's made our marriage work."
Gellar and Prinze met on the set of the 1997 movie I Know What You Did Last Summer. The couple have since co-starred in Scooby-Doo and its sequel, and voiced characters in Happily N'Ever After.