The 35-year-old actress, who stars with Rihanna in the new film Ocean's 8, recalled on Thursday's episode of The Ellen DeGeneres Show how the 30-year-old singer and their co-stars boosted her confidence on the movie's set.
"It was really significant for me because it was my first movie after having my son," Hathaway said, referencing 2-year-old Jonathan. "After I had my son, the weight was really slow to come off and so I was a different size than I normally am."
"I walked on the set, and, you know, my weight's a little up and I'm just aware of it," she recounted. "And Sandy Bullock looks up and goes, 'Looking good, mama!' It made me feel amazing! Cate Blanchett's like, 'Nice jeans, Hathaway!'"
Hathaway said Rihanna was more direct with her compliment.
"Rihanna looks up and goes, 'Damn girl, you got a [expletive]!'" she recalled. "And of course I freaked out and loved it so much. I was like, 'Really?!' And she goes, 'You got a [expletive] like me!'"
Hathaway is parent to Jonathan with her husband, Adam Schulman. She preemptively addressed critics in an Instagram post in April after gaining weight for a new movie.
"I am gaining weight for a movie role and it is going well. To all the people who are going to fat shame me in the upcoming months, it's not me, it's you," the star wrote.
Ocean's 8 opens in theaters Friday, June 8. Hathaway, Rihanna and their co-stars dazzled at the film's New York premiere Tuesday.