Born on the South Side of Chicago in the Grand Crossing neighborhood, Comer graduated from the Paul Revere Elementary School in 1942 and Hyde Park High School in 1946. He became a copywriter at Young & Rubicam in Chicago. After 10 years, having been an avid sailor from childhood, he began his own business supplying sailing equipment.
In the Spring of 1963 Comer and his close friend Robert Halperin, Halperin's fellow sailor Richard Stearns (with whom Halperin won a gold medal in yachting at the 1963 Pan American Games), and two of Stearns' employees founded Lands' End. They started it originally as a retailer of sailing supplies and equipment (based on a mail order equipment business begun a year earlier). Comer served as president through 1990 (including following Lands' End's registration as a public company), when he stepped down from active management. He remained a major shareholder until Lands' End was acquired by Sears in 2002.
Comer was a long-time philanthropist, donating money to causes including children's health care, education and the study of global climate change. He opened the Gary Comer Youth Center which houses among other things Gary Comer College Prep - a campus of the Noble Network of Charter Schools.
Comer was a major contributor to the University of Chicago, providing more than $84 million in donations leading to the establishment and expansion of the Comer Children's Hospital at the University of Chicago.
Comer died of prostate cancer on October 4, 2006 at his home surrounded by his family
- "American National Business Hall of Fame". Anbhf.org. Retrieved July 12, 2011.