He was a member of the band the Flying Burrito Brothers, and worked extensively as a session musician, playing pedal steel guitar for Joan Baez, Jackson Browne, The Byrds, Leonard Cohen, Joe Cocker, Rita Coolidge, Eagles, The Everly Brothers, Ringo Starr, John Lennon, The Steve Miller Band, Joni Mitchell, The Rolling Stones, Stevie Wonder, Spencer Davis, Little Richard, Linda Ronstadt, Jimmie Spheeris and many others.

After uncredited work on The Wonderful World of the Brothers Grimm (1962), The Outer Limits (1963–1965), and 7 Faces of Dr. Lao (1964), Kleinow became closely associated with the long-running children's series Gumby and Davey and Goliath while moonlighting in the city's country-oriented nightclubs as a member of Smokey Rogers & the Western Caravan (from which his distinctive nickname originated) and the Detours (often deputizing for bandleader Red Rhodes, then frequently employed as a session musician).

Through this scene he became acquainted with Chris Hillman and Gram Parsons of the Byrds in 1968, helping the group to replicate their newly country-infused sound onstage with banjoist Doug Dillard on several local club dates.

His unorthodox style of playing would immediately influence a number of second-generation country rock pedal steel players, including Jerry Garcia, Buddy Cage of the New Riders of the Purple Sage and his eventual replacement in the Burrito Brothers, session musician Al Perkins.

Favoring a relatively abstemious and reclusive lifestyle in comparison to some of his bandmates (nevertheless, according to bassist Chris Ethridge, he "loved to drink wine" and frequently exhibited science fiction films at the "Burrito Manor" shared by Parsons and Hillman in Reseda throughout 1968); intolerant of the group's infamously erratic live performances; and increasingly disenchanted by his exclusion from the creative process—including the diminution of his parts in released mixes and the summary rejection of his songwriting efforts—Kleinow eventually left the Flying Burrito Brothers in 1971.

He appeared on albums by Joe Cocker (Joe Cocker!, 1969), Delaney, Bonnie and Friends (To Bonnie from Delaney, 1970), Joni Mitchell (Blue, 1971), Billy Joel (Cold Spring Harbor, 1971), Little Feat (Sailin' Shoes, 1972), Little Richard (The Second Coming, 1972), Sandy Denny (Sandy, 1972), Frank Zappa (Waka/Jawaka, 1972), the Bee Gees (Life in a Tin Can, 1973), Yoko Ono (Feeling the Space, 1973), John Lennon (Mind Games, 1973), John Cale (Paris 1919, 1973), Linda Ronstadt (Heart Like A Wheel, 1974), Harry Nilsson (Pussy Cats, 1974), Stevie Wonder (Fulfillingness' First Finale, 1974 and Songs in the Key of Life, 1976), Fleetwood Mac (Heroes Are Hard to Find, 1974), and Leonard Cohen (Death of a Ladies' Man, 1977).

Following a second stint on Davey and Goliath in 1972, he returned to visual effects in earnest as an animator on Sid and Marty Krofft's Land of the Lost (1974–1976) and created the dinosaurs for the comic film Caveman (1981).

[7] Three months before his death, local singer songwriter Jan White and bassist Pat Campbell gave Kleinow a final private concert, performing several Gram Parsons songs for him, set in the nursing facility's garden.