The 46-year-old actress said on Thursday's episode of Today that she was initially "scared" to help Jodi Kantor and Megan Twohey with their New York Times article about Weinstein's misconduct.
"I was really scared," Paltrow recalled. "I think society had shown us only basically examples where women coming forward ended up not being advantageous for the woman, but I really felt like it was time."
Paltrow said she was also inspired by Apple, her now 15-year-old daughter with ex-husband Chris Martin.
"Having a teenage daughter that's the love of my life and worrying about her going into the workplace, and feeling like if there was ever a chance that there could be a cultural shift that I could participate in," the star said.
"I never could have imagined that, collectively, a shift this seismic could have happened. But I feel proud that I have a small part in it," she added.
Paltrow and other women accused Weinstein of sexual assault and harassment in Kantor and Twohey's October 2017 exposé. Kantor and Twohey published a book about their investigation, She Said, this month.
Paltrow will next star in the Netflix series The Politician, created by her husband, Brad Falchuk, Ryan Murphy and Ian Brennan. She said on Today that Falchuk convinced her to join the show, which debuts Friday.