The Buffy the Vampire Slayer star posted a black-and-white throwback picture of the couple at a film premiere to mark the event.
In her humorous caption, the actress posted: "I was looking for the perfect present for your bday @realfreddieprinze, but then I realized… I am present enough."
WATCH: Sarah Michelle Gellar's daughter shows off impressive trampolining skills
And that's not where Sarah's jokes ended, as she threw in a small Tiger King reference, adding: "But I do make you this promise, I will NEVER feed you to the tigers. Happy birthday FP!!"
Fans loved the Scooby-Doo star's hilarious tribute, with Amanda Kloots writing: "Hahahahah awww this is so cute." Another added: "I'm dying at the caption."
Many other fans paid their own tribute to the couple, who met on the set of I Know What You Did Last Summer.
The celebrity couple have been married since 2002
"You guys are the best," wrote one, while another said: "Still the hottest and solid couple."
One admiring fan wrote: "Hahaaa. Happy birthday @realfreddieprinze you guys are forever so cute."
It wasn't just witty picture captions that Sarah got Freddie, as the star posted on her stories two extravagant cakes from The Pie Room by Gwen.
"@realfreddieprinze, it's still your birthday tomorrow, right?" she joked alongside a picture of a delicious looking coconut cake.
Sarah and Freddie had some delicious looking cakes
Although Sarah opted for a funny post to mark her husband's birthday, the actress has done more serious posts for others.
Paying tribute to her Buffy co-star, Seth Green when it was his birthday last month, the actress wrote: "Sadly, this is the longest I've gone without a hug from you EVER.
"So on your birthday, this digital hug and trip down memory lane will have to do. Happy birthday my dear friend, I miss you madly."
Seth, who is known for his roles in the Austin Powers films and Family Guy wrote back: "You're truly the best. I feel so lucky to have you as a friend all this time. Such a consistently wonderful and inspiring human – love you my friend."
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