Little was one of three sons of a physician. Little had a gift for impersonations since his school days and began performing professionally in night clubs at 17. He acted in Ottawa's Little Theatre and became a successful disc jockey who frequently incorporated impersonations into his show. In 1963, Little was asked to audition by Mel Torme, who was producing a new variety show for Judy Garland. Little's audition won him the job and he broke into American show business.

Little was a frequent guest on variety and talk shows. He was a regular guest on Dean Martin's Celebrity Roasts in the 1970s and was also a regular on The Julie Andrews Hour in 1973. He was named Comedy Star of the Year by the American Guild of Variety Artists in 1974. He hosted The ABC Comedy Hour (also known as KopyKats) in 1972, The Rich Little Show in 1976, and The New You Asked For It in 1981. Little has also appeared in several movies and released nine albums.

Little has been active in several charities including the Juvenile Diabetes Fund and the Children's Miracle Network. He has been named to Miami Children's Hospital International Pediatrics Hall of Fame and been honored by the naming of the Rich Little Special Care Nursery at Ottawa Civic Hospital.

Little was married to Jeanne Worden from 1971 until their divorce in 1989. The couple have a daughter, Bria. He married Jeannette Markey in 1994; they divorced in 1997. Little married his current wife, Marie Marotta, in 2003.

While Little is still a Canadian citizen, he resides in Las Vegas, Nevada, where he performs regularly.