The Legally Blonde beauty was joined by stars including actress Paula Patton at The Avon Foundation's Champions Who Change Women's Lives event in New York to raise funds for the campaign, for which she is an honorary chairperson.
And Witherspoon is delighted to be associated with such a prominent organisation.
She says, "It was just great... working with Avon and this incredible foundation and what they do. (The fundraiser) was just an extension of what they've been doing."
Witherspoon is also a global ambassador for the Avon cosmetic's brand.