His mother is former actress Cynthia Stone, who went on to marry Cliff Robertson in 1957 after divorcing Jack the year before.
His father, Jack Lemmon, worked with him in his initial movie credit, Airport '77 (1977), where he played a radio operator.
Lives in Connecticut with his wife, Gina Raymond, and their three children: daughter, Sydney Lemmon (Sydney Noel Lemmon) (born in 1990), and two sons, Christopher Lemmon, Jr. and Jon Lemmon (Jonathan Lemmon) (born in 1994).