Leslie West first gained recognition as the lead guitarist for the Vagrants, a locally popular 1960s Long Island group. One of that band's singles was produced by Felix Pappalardi, a bass player who also produced Cream. After the Vagrants and Cream split up, Pappalardi played bass on and produced West's debut solo album, Mountain (July 1969). Following its release, the two teamed up with drummer Norman Smart (soon replaced by Corky Laing) and keyboard player Steve Knight to form the band Mountain. They cut the albums Climbing! (February 1970, a gold-selling LP featuring the Top 40 single "Mississippi Queen"), Nantucket Sleighride (January 1971, which also went gold), and Flowers of Evil (November 1971). In 1972, Pappalardi left Mountain to return to producing. (Posthumous record releases included Mountain Live (The Road Goes on Forever) in April 1972 and The Best of Mountain in February 1973.)

West and Laing joined with former Cream bassist Jack Bruce to form West, Bruce Laing. The trio recorded two studio albums, Why Dontcha (October 1972) and Whatever Turns You On (July 1973). A live album, Live 'N' Kickin', was released in April 1974. Bruce quit in the summer of 1973, and West and Laing briefly formed Leslie West's Wild West Show. West, Pappalardi, Alan Schwartherg (drums), and Bob Mann (keyboards) then re-formed Mountain, recording a double-live album, Twin Peaks (February 1974), in Osaka, Japan, in August 1973. This was followed by a Mountain studio album, Avalanche (July 1974), made by West, Pappalardi, Laing, and Knight. Then Mountain split again, and West formed the Leslie West Band, releasing The Great Fatsby (April 1975), which featured Mick Jagger, and The Leslie West Band (1976), which featured Mick Jones, later of Foreigner.

Bedeviled by substance abuse problems, West retired from music for a time, then cleaned up and again re-formed Mountain with Laing and bassist Mark Clarke (Pappalardi had died in 1983) for Go for Your Life (March 1985). The group broke up again, and West made Theme (1988), again teaming with Jack Bruce. West participated in the Guitar Speaks (1988) and Night of the Guitar (1989) recordings of legendary rock guitarists for IRS Records' Illegal subsidiary. His next solo album was Alligator (August 1989), followed by Dodgin' the Dirt (1994).

In 1994, West and Laing teamed with ex-Jimi Hendrix Experience bassist Noel Redding in another edition of Mountain, recording two tracks for the compilation Over the Top (1995). The solo As Phat as It Gets followed in 1999. After an album for Voiceprint, Guitarded, in 2004, West released two blues-inflected albums for Blues Bureau International, 2005's Got Blooze and 2006's Blue Me. He lost a leg due to complications from type 2 diabetes in June 2011, but it didn't slow him down much. He released Unusual Suspects, which featured guest spots from guitarists Billy Gibbons, Slash, Zakk Wylde, Joe Bonamassa, and Steve Lukather three months later in September. 2013's Still Climbing was another star-studded set that included contributions from bluesmen Johnny Winter and Jonny Lang, Twisted Sister vocalist Dee Snider, and Creed and Alter Bridge guitarist Mark Tremonti. West spent less time in the studio after releasing Soundcheck in 2015, but he continued to tour regularly until 2019, when he was sidelined by ongoing health problems. Leslie West died on December 22, 2020; he was 75 years old. ~ William Ruhlmann, Rovi