Haskell was born in Brooklyn, New York. He entered the musical business through being hired to do arrangements with Imperial Records. He became the arranger of choice for Ricky Nelson and arranged such hits as "There's Nothing I Can Say" (1964). In the late 1960s and early 1970s Haskell was the arranger of choice for The Grass Roots. He arranged the signature horn section on Chicago's worldwide hit "If You Leave Me Now" and also provided horn & string arrangements for Blondie's 1980 album Autoamerican.
He entered the motion picture soundtrack industry in 1960 as an uncredited orchestrator for Dimitri Tiomkin's The Alamo and composed his first score the following year Love in a Goldfish Bowl. His composition The Silly Song became the theme song of American television's The Hollywood Squares.
In addition to composing and arranging, Haskell would often act as conductor and selected the musicians used.
His birthday is widely reported as 1936 because he lied about his age, figuring he would get more work if people thought he was younger. A statement from his daughter published by The Musicians Union of Los Angeles gives the correct birthday in 1926.
Haskell was awarded an Emmy for Outstanding Achievement in Music Composition for a Special (Dramatic Underscore) for See How She Runs (1978) and has received two other nominations. He was awarded Grammies for his arrangements of Ode to Billie Joe recorded by Bobbie Gentry, Bridge Over Troubled Water recorded by Simon and Garfunkel, and If You Leave Me Now recorded by Chicago.
- Love in a Goldfish Bowl (1961)
- I'll Take Sweden (1965)
- Town Tamer (1965)
- Apache Uprising (1965)
- Red Tomahawk (1966)
- Johnny Reno (1966)
- Waco (1966)
- Hostile Guns (1967)
- Fort Utah (1967)
- The Wicked Dreams of Paula Schultz (1968)
- Arizona Bushwhackers (1968)
- Buckskin (1968)
- The Thousand Plane Raid (1969)
- Zachariah (1971)
- The Honkers (1972)
- Night of the Lepus (1972)
- Dirty Mary, Crazy Larry (1974)
- Death Game (1977)
- Joyride (1977)
- Hughes and Harlow: Angels in Hell (1978)
- A Christmas to Remember (1978)
- The Jericho Mile (1979)
- Guyana: Crime of the Century (1979)
- Goldie and the Boxer (1979)
- The Jayne Mansfield Story (1980)
- Hard Country (1981)
- Jake Spanner, Private Eye (1989)
- The Hollywood Squares (1965) (composer)
- Bewitched (1966) (composer)
- The Andy Williams Show (1968) (composer)
- The Doris Day Show (1969) (composer)
- Curiosity Shop (1971)
- Land of the Lost (1974) (composer)
- Cathy (1987) (composer)
- Silent Möbius (1998) (main composer with Suzie Katayama and Kenichi Sudo)
- "LondonJazz: TRIBUTE: Jimmie Haskell (1936- 2016)". Londonjazznews.com. 2016-02-07.
- "Jimmie Haskell". IMDb.com. Retrieved 15 August 2018.
- "Jimmie Haskell memories of The Grass Roots", The-grassroots.com, retrieved 2014-08-29
- Billboard - Google Books. 1974-05-04. Retrieved 2012-02-20.
- "Final Note: Jimmie Haskell". afm47.org. 2016-02-26.
- Los Angeles (2004-08-27). "Jimmie Haskell: The Man Behind the Music - 2004-08-27 | News | English". Voanews.com. Retrieved 2012-02-20.