Michelson announced his intent to launch a medical philanthropic venture in a 2005 New York Times article, at that time planning to apply at least $200 million to explore and scale leading edge medical Technology, like nanotechnology and stem cell research. Founded in 1995, The Gary Karlin Michelson, M.D. Charitable Foundation, Inc. was rechristened the Michelson Medical Research Foundation in 2005. With no paid officers and an initial contribution of $100 million later augmented by Michelson's add-on contributions, the nonprofit does not accept donations.

In 2008, Michelson's Found Animals foundation launched the Michelson Prize and Grants in Reproductive Biology an international competition with a 25 million dollar prize that represents a unique experiment in innovation aimed at solving the Problem of pet overpopulation. His goal is to encourage researchers from a wide variety of scientific fields to take on the challenge of non-surgical pet sterilization. Recognizing that interested parties may not have access to funds the research and testing would require, also offered is the companion Michelson Grants in Reproductive Biology that will provide up to $50 million in funding for promising research. The Michelson Prize seeks to make sterilization accessible and affordable worldwide and aid developing countries where this Problem is even greater.

With a budget of 15 million dollars as of November 2013, 65 full-time employees and 137,000 volunteer hours to date, Found Animals provides no cost spay and neuter services to low income households, a grant program supporting spay/neuter and surrender prevention programs, a kitten foster program which saved more than 1,000 kittens in 2015 and the Saving Pets Challenge which raised $1 Million for animal welfare organizations nationwide.

In the December 2015 issue of Forbes Magazine, Gary K. Michelson was featured alongside Warren Buffett, william A. Ackman, Michael Milken, Michael J. Fox as one of "10 People with Big Ideas to Change the World".

In the August 2016 special issue of the Los Angeles Business Journal, Dr. Gary Michelson was listed among the 500 most influential people in Los Angeles.

In January 2014 it was announced that Michelson gifted $50 million to the University of Southern California for the USC Michelson Center for Convergent Bioscience. The venue opened its doors on November 1st, 2017.

In a program directly acknowledged by the L.A. Mayor’s office, Dr. Michelson’s Found Animals Foundation paid for all the costs of anyone who would rescue a dog or cat scheduled for euthanasia. It is estimated that Dr. Michelson has thus far devoted a total of $300 million to various causes.