Bryce Dallas Howard has said she was scared for asking for more pay in the past in case she lost roles.
The Black Mirror and Jurassic World actress said the salaries paid to women were "astronomically different" to those paid to men.
Speaking to Redbook magazine, the 37-year-old said: "I didn't want people to think I wasn't grateful for opportunities."
However, she said the Time's Up movement has inspired her to change.
She also added: "I get scared off by every threat during a negotiation.
"They'll say, 'we'll just have to find someone else', and I back off. You can't do that."
Howard also said that negotiating was easier for more established male actors who can afford to "have a manager as well as an agent".
"That's 20% out of your paycheck rather than 10%," she added.
The actress is the daughter of film-maker Ron Howard, who has directed films including Apollo 13, Frost/Nixon and Solo: A Star Wars Story.
"Even my dad has been shocked at how expensive it is to be a woman in the industry", she added.