An early musical success for McCann was his winning of a Navy talent contest for singing; this led to an appearance on The Ed Sullivan Show. McCann's main career began in the early 1960s when he recorded as a pianist with his trio for Pacific Jazz Records.
In 1969, Atlantic Records released Swiss Movement, a recording of McCann with frequent collaborator, saxophonist Eddie Harris, and guest trumpeter Benny Bailey at that year's Montreux Jazz Festival. The album contained the song "Compared to What", and both the album and the single were huge Billboard pop chart successes. "Compared to What" featured political criticism of the Vietnam War. The song was not written by McCann; fellow Atlantic composer/artist Eugene McDaniels wrote it years earlier. "Compared to What" was initially recorded and released by soul vocalist Roberta Flack. Her version appeared as the opening track on her debut recording, First Take (1969).
After the success of Swiss Movement, McCann – primarily a piano player – began to emphasize his rough-hewn vocals more. He became an innovator in the soul jazz style, merging jazz with funk, soul and world rhythms; much of his early 1970s music prefigures the Stevie Wonder albums of that decade. He was among the first jazz musicians to include electric piano, clavinet, and synthesizer in his music.
In 1971, he and Harris were part of a group of soul, R&B, and rock performers – including Wilson Pickett, The Staple Singers, Santana and Ike & Tina Turner – who flew to Accra, Ghana for a historic 14-hour concert before more than 100,000 Ghanaians. The March 6 concert was recorded for the documentary film Soul To Soul. In 2004 the movie was released on DVD with an accompanying soundtrack album.
Les McCann discovered Roberta Flack and arranged an audition which resulted in a recording contract for her with Atlantic Records.
- It's About Time (Pacific Jazz, 1959 ) with Teddy Edwards
- Les McCann Ltd. Plays the Truth (Pacific Jazz, 1960)
- Les McCann Ltd. Plays the Shout (Pacific Jazz, 1960)
- Les McCann Ltd. in San Francisco (Pacific Jazz, 1960 )
- From the Top of the Barrel (Pacific Jazz, 1960 )
- "Groove" (Pacific Jazz, 1961), with Richard "Groove" Holmes and Ben Webster
- Pretty Lady (Pacific Jazz, 1961); reissued as Django
- Les McCann Sings (Pacific Jazz, 1961), orchestra directed by Gerald Wilson
- Les McCann Ltd. in New York (Pacific Jazz, 1961) with Stanley Turrentine and Blue Mitchell
- Les McCann Ltd. Plays the Shampoo (Pacific Jazz, 1961 )
- New from the Big City (Pacific Jazz, 1961 )
- Stormy Monday (Capitol, 1962) with Lou Rawls
- Somethin' Special (Pacific Jazz, 1962 ), with Richard "Groove" Holmes
- On Time (Pacific Jazz, 1962) with Joe Pass
- The Gospel Truth (Pacific Jazz, 1963)
- Soul Hits (Pacific Jazz, 1963) with Joe Pass
- Jazz Waltz (Pacific Jazz, 1964) with the Jazz Crusaders
- Spanish Onions (Pacific Jazz, 1964)
- A Bag of Gold (Pacific Jazz, 1960-64 )
- McCanna (Pacific Jazz, 1964)
- McCann/Wilson (Pacific Jazz, 1965), with the Gerald Wilson Orchestra
- But Not Really (Limelight, 1965)
- Beaux J. Pooboo (Limelight, 1965)
- Live at Shelly's Manne-Hole (Limelight, 1966)
- Les McCann Plays the Hits (Limelight, 1966)
- Bucket O' Grease (Limelight, 1966)
- Live at Bohemian Caverns - Washington, DC (Limelight, 1967)
- Much Les (Atlantic, 1969)
- Swiss Movement (Atlantic, 1969), with Eddie Harris
- Comment (Atlantic, 1970)
- Second Movement (Atlantic, 1971), with Eddie Harris
- Invitation to Openness (Atlantic, 1972)
- Talk to the People (Atlantic, 1972)
- Live at Montreux (Atlantic, 1973)
- Layers (Atlantic, 1974)
- Another Beginning (Atlantic, 1974)
- Hustle to Survive (Atlantic, 1975)
- River High, River Low (Atlantic, 1976)
- Change Change Change; Live at the Roxy (1977, ABC)
- Music Lets Me Be (1977, ABC Impulse)
- The Man (1978, A&M)
- Tall, Dark & Handsome (1979, A&M)
- The Longer You Wait (1983, JAM)
- McCann's Music Box (1984, JAM)
- The Butterfly (1988, Stone)
- More of Les (1989)
- Relationships: The Les McCann Anthology (1993, Rhino/Atlantic)
- On the Soul Side (1994, MusicMasters)
- Piano Jazz (1996, NPR Piano Jazz Series), featuring Marian McPartland
- Listen Up!! (1996, Music Masters)
- Pacifique (1998, Music Masters), with Joja Wendt
- How's Your Mother? (1998, 32JAZZ)
- Pump It Up (2002, France)
- Jazz Legend Project (2004, Megaphon)
- Tell It Like It Tis (Pacific Jazz, 1961 )
- With Stanley Turrentine
- That's Where It's At (Blue Note, 1962)
- Doldinger Jubilee '75, 1975, Atlantic
- "Compared to What" was featured in "Lockdown", the season two episode of Lost.
- The live version of "Compared to What" was featured in the Martin Scorsese film Casino, during the scene where the organizational hierarchy of the casino is being explained.
- "Compared to What" has been a featured song in the 2007 tour of American Idol Season 5 winner Taylor Hicks.
- McCann's song "Valllarta(Skit)" was sampled by the late rapper The Notorious B.I.G. in the song "The Ten Crack Commandments" off his album Life After Death.
- The song "Roberta" was sampled on Afu-Ra's "Whirlwind Thru Cities".
- The beginning of "Sometimes I Cry" was sampled by Massive Attack to create their song "Teardrop".
- "Behind Bars" by Slick Rick also samples "Sometimes I Cry".
- "The song "Music lets me be" was used in the intro of Gang Starr's "You know my steez".
- The beginning of the song "The Harlem Buck Dance Strut" is used in the Daddylonglegs (Howie B) song "Giddy up" and is used in full on Ice-T's "Soul on Ice" from the album Power.
- McCann's song "Benjamin" (1969) was sampled by French rap band IAM in the song "C'est donc ça nos vies" and in "Right Back at You" by New York rap duo Mobb Deep.
- "Rather Unique" by AZ samples the ending chords of "Anticipation".
- Feather, Leonard & Gitler, Ira (2007) The Biographical Encyclopedia of Jazz, p448. Oxford University Press.
- Yanow, Scott. "Les McCann: Biography". Allmusic. Retrieved 2010-10-17.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
- Olewnick, Brian. "Swiss Movement: Review". Allmusic. Retrieved 2010-10-17.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>