"This movement is bigger than just a change in our industry alone".
The letter calls for an end to harassment and abuse due to an "imbalance of power" across all industries as well as highlighting that the gender pay gap for women in their 20s in Britain is now "five times greater than it was six years ago".
"There is no question that Time's Up should be and will be a global movement".
Watson is one of the first donors to the fund, which was set up by the 190 women who signed the open letter, along with a group of 160 academics, activists and charity workers.
Many women attending tonight's awards have indicated they will wear black in solidarity with the Hollywood based Time's Up movement.
The description on the page explains that the fund will be overseen and managed by leading United Kingdom women's fund Rosa, and will address what it refers to as "priority needs" like people in low paid, part-time and freelance employment and 'those who face intersecting disadvantages related to their race, age, class, immigration status, disability or sexuality'.
"While we know women are disproportionately affected by this abuse, we also know there are men in our industry and others that have been subjected to harassment and abuse as part of this system of patriarchal power. It was certainly not to be discussed, let alone addressed", they wrote.
Jennifer Aniston, Meryl Streep and Reese Witherspoon each donated $500,000 to the organization's legal defense fund, which will provide financial assistance to victims of sexual harassment, assault or abuse while at work, regardless of the industry they are employed in.
Watson, Knightley, Mbatha-Raw, and Whittaker were joined by the likes of Emma Thompson, Carey Mulligan, Kate Winslet, Saoirse Ronan, Gemma Arterton, Tessa Thompson, Gemma Chan, Claire Foy, and Sophie Okonedo in adding their signatures to the call for action, titled Dear Sisters, which was published in The Observer newspaper.
It reads: "As we approach the Baftas - our industry's time for celebration and acknowledgment, we hope we can celebrate this tremendous moment of solidarity and unity across borders by coming together and making this movement global". The open letter, which also features activists and charity workers, contains almost 200 signatures.