Gaga praised her cast members and Cooper for putting "every last drop of blood from their heart and their veins on set every single day", according to the hollywoodreporter.com.
"I watched (Cooper) work tirelessly on this film, giving it everything, and you never stopped. Nobody here did," she said.
The words caused the audience to break into applause which instantly drew a standing ovation.
Gaga was seen breaking into tears as she covered her face with her hands. She lifted her face and mouthed "Thank you" as the audience began to cheer louder.
She has received critical acclaim for her performance in the film with critics calling her "dynamite". "A Star Is Born" will be in theatres in the US on October 5.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)