The initiative follows the rise of the #MeToo hashtag, which saw people sharing their experiences of sexual harassment on social media, in response to the allegations made about various men in Hollywood in light of the Weinstein scandal.
Much of the cash will be used to swell a legal defence fund created to help women protect themselves against sexual misconduct in the workplace, and encourage them to speak out about it. Taylor Swift and Oprah Winfrey donated £76,000 each, while Cate Blanchett, Emma Stone, and Jessica Chastain have also dug deep for the cause.
"Harassment too often persists because perpetrators and employers never face any consequences", read a "letter of solidarity" on the group's website.
The movement also launched the Commission on Eliminating Sexual Harassment and Advancing Equality in the Workplace in mid December.
The initiative has been described as a "unified call for change from women in entertainment for women everywhere". Time's up on tolerating discrimination, harassment or abuse.
The group insists that more women must be brought into positions of power and leadership, while every woman should have equal benefits, opportunities, pay and representation.
The letter ran as a full-page ad in The New York Times and Spanish-language newspaper La Opinion.
A push to reach gender parity in Hollywood studios and talent agencies; and a call for women walking the red carpet at the Golden Globes to wear black as a sign of protest and solidarity.
Other prominent women lending their names to the Time's Up cause are actresses Natalie Portman, America Ferrera, Amy Schumer, Halle Berry, Julianne Moore, Keira Knightley, Nicole Kidman, Penelope Cruz, Reese Witherspoon, Scarlett Johansson, Susan Sarandon, Uma Thurman and Viola Davis; producer Shonda Rhimes; Universal Pictures chair Donna Langley; feminist activist Gloria Steinem; lawyer and ex-Michelle Obama chief of staff Tina Tchen and Nike Foundation co-chair Maria Eitel.