The event, which will take place at Los Angeles' Beverly Hills Hotel on 30 September (10), will also fete actresses Diane Lane, Amy Adams, Natalie Portman and talent manager Suzan Bymel.
The ladies have been selected as the industry publication's Lifetime Impact Honorees for making a significant difference to their chosen causes.
Holmes will be honoured for her work on behalf of the Dizzy Feet Foundation, Mendes for Art of Elysium and Garner for Save the Children.
Meanwhile, Adams will be recognised for her efforts with Ghetto Film School, Lane for Heifer International, Portman for charitable microfinance organisation FINCA, and Bymel for her contributions to Global Creative Forum.
The group follows in the footsteps of last year's (09) first-ever honorees, including Christina Applegate, Anne Hathaway, Sigourney Weaver, Christina Aguilera, and movie mogul Sherry Lansing.