The 26-year-old model shared the happy news with her 16 million Instagram followers as she revealed their loved-up wedding photos.
Emily Ratajkowski was joined by social media star The Fat Jewish, real name Josh Ostrovsky, to be in attendance as a witness as the pair tied the knot at New York City Hall.
Sebastian’s friend and Good Time co-director Josh Safdie was also present.
Dressed in a stylish yellow suit and a chic black hat with a net veil, the brunette bombshell shared a series of snaps on her story, saying: “Sooo…
“I have a surprise,” she captioned the second shot, which saw her cuddling her pet pug as she posed in the eye-catching ensemble.
A third picture showed producer and actor Sebastian kissing her on the cheek and holding her hand.
“I got married today!” she said in the caption.
Emily’s shock wedding came as a surprise to her legions of fans, occurring just weeks after news broke that she was no longer in a relationship with ex-boyfriend Jeff Magid, although the pair are thought to have split several months ago.
She also shared an adorable shot of her new husband pulling her in close for an intimate embrace as the pair beamed for the camera.
Her fans flooded to the comments section to share their reaction to Emily’s marriage, with one exclaiming: “WHAT?!”
“WTF?!?! I don’t believe…” a second said, while a third seemed disappointed, adding: “My heart just broke into a million pieces.”
“Wait, when did she and Magid break up?” another asked.
Many more of Emily’s followers sent their congratulations to the newlyweds.
The busty star had been dating music producer Jeff for three years.
She only confirmed her romance with Sebastian on Valentine’s Day when pictures of the couple kissing emerged.
Sebastian’s filmography includes producing 2017 crime thriller Good Time, which starred Robert Pattison.
Emily, who boasts a role in 2018 David Fincher movie Gone Girl, is best known for her eye-poppingly racy Instagram uploads.