The Irish actress, whose leading role sees her play a young Irishwoman in New York in the 1950s, won the New Hollywood Award for her performance on Sunday.
Ronan was born in New York City to Irish parents. They returned to Ireland when she was three.
Robert De Niro, Carey Mulligan, and Will Smith were among the big winners at the ceremony.
De Niro was presented with the Hollywood Career Achievement Award at the 19th annual Hollywood Film Awards in Beverly Hills.
Mulligan was given the Hollywood Actress Award for her role in Suffragette and Smith took home the Hollywood Actor Award for his portrayal of a doctor in new film Concussion, about the discovery of brain trauma in a professional American football player.
Ronan said her movie resonated with her as her own move to London made her feel like “an open wound emotionally”.
She said the move to the UK capital resulted in a feeling of loneliness and homesickness which meant her personal life and character’s life “ran parallel in every way”.
In an interview with the Radio Times, she said: “I needed to leave Ireland.
“I love it but I needed to be anonymous. I was recognised quite a bit at home and I was very aware of growing up in an industry where everything is done for you.
“By the time I did Brooklyn, I was like an open wound emotionally. I felt very vulnerable. It was the first time ever, professionally, where my personal life and my character’s life ran parallel in every way.
“It was like being forced to stare at yourself in a mirror close-up and not being able to look away.”