The move came after the singer spent two weeks with hardcore junkies to research for her latest role of singer Etta James, whose early career was blighted by heroin addiction, reports the Daily Star.
Knowles visited New York's Phoenix House for the research and was moved to tears as she watched down-at-heel drug abusers go through detox misery after hitting rock bottom at the Phoenix House centre in Brooklyn, New York.
She was so moved by the work of Phoenix House staff - who treat 5,000 addicts a day in the US - that she pledged every penny of her pay cheque to helping them.
Karen Sodomick, marketing chief of the Phoenix House chain, confirmed Beyonce had given the 'overwhelmingly generous' gift.
However, she said: "Beyonce wants to remain a quiet supporter."