The 49-year-old star took home the award for outstanding performance by a male actor in a supporting role for his acting in the critically acclaimed movie.
He won the award beating the likes of Steve Carrell in "Battle of the Sexes", Willem Dafoe in "The Florida Project", Woody Harrelson in "Three Billboards Outside Ebbing, Missouri", and Richard Jenkins in "The Shape of Water".
In his acceptance speech, Rockwell said, “Wow! This is awesome" before thanking his co-nominees, costars, and his “incredible ensemble.”
He said: “My mom and dad were actors, they dragged me to rehearsals when I was a baby and I slowly realised that these people are nuts. If you’re a struggling actor out there, hang in there!”
With a glint in his eye, Rockwell also thanked his "beloved" wife Leslie Bibb — “who puts up with me. I love you baby, I love you” — and his co-star Frances McDormand. “I stand shoulder to shoulder with you and all these incredible women in this room to try to make things better,” he said. “It’s long overdue.”
Just before Rockwell entered the awards venue, he was captured posing with Bibb and boasting of his love of 10 years and counting. The two were quoted giving tips on maintaining a successful relationship.
When Rockwell said it was "communication", Bibb said, "good sex" to which Rockwell added, "communication and good sex".
Bibb then continued with "humour" to which Rockwell added, "Bibb is very funny" and "humour is very important".
Earlier this month, Rockwell won the Golden Globe for his role in the film.