Her portrayal of Queen Anne beat an impressive group of competitors, including Yalitza Aparicio in "Roma," seven-time Oscar nominee Glenn Close in "The Wife," Lady Gaga in "A Star Is Born" and Melissa McCarthy in "Can You Ever Forgive Me?"
During Colman's acceptance speech, she was overcome with emotion from winning her first Oscar.
"This is hilarious. I got an Oscar," she said. "Okay. I have to thank lots of people. If I forget anybody, I'll find you later and give you a massive snog, I'm sorry I might forget now."
"My best director, and the best film -- and both Emily and Rachel, the two loveliest women in the world to fall in love with and to go to work with every day," she said, referring to co-stars Emma Stone and Rachel Weisz.
"I mean you can image, it wasn't a hardship," she added.
Colman also took time to commend her fellow nominees.
"To be in this category with these extraordinary women -- Glenn Close, you've been my idol for so long," said Colman. "This is not how I wanted to it to be, and I think you're amazing and I love you very much."
The actress also mentioned her family, including her kids, her husband and her agent, acknowledging their support.
She finished her speech by sharing an inspirational message to aspiring actresses who might be watching her acceptance speech.
"Any little girl who is practicing their speech on the telly, you never know. I used to work as a cleaner, and I loved that job. I did spend quite a lot of time imagining this."
The actress is also a two-time Golden Globe winner.