After considerable research the only mention of Charlie Chaplin’s philanthropic activities that I could find was that in 1921, he was one of several Hollywood stars to form and help raise funds for The Motion Picture Relief Fund (MPRF). The fund was designed to help struggling actors.
In 1940, it became known as the Motion Picture & Television Country House and Hospital “cementing its status as a primary health-care provider for industry workers.” Other than helping in the fundraising efforts, I’m not sure how else Chaplin helped. I’m not even sure he donated any of his own money.