Mike Mainieri was born July 4, 1938, in New York City, and first played vibraphone professionally at fourteen, touring with Paul Whiteman in a trio called Two Kings & a Queen. At twenty he won Down Beat's International Jazz Critic's Award. He played with Buddy Rich's bands from 1956 to 1963, then became a busy studio musician on numerous pop records, also working with Benny Goodman, Coleman Hawkins, and Wes Montgomery (1967-1968), and playing in the early fusion band Jeremy & the Satyrs.

In 1979 he formed Steps, later renamed Steps Ahead, an all-star jazz-fusion band whose original lineup included saxophonist Michael Brecker, whose own career is covered in full in his JazzProfiles.com profile, keyboardist Don Grolnick, bassist Eddie Gomez, and drummer Steve Gadd; drummer Peter Erskine, whose own career is covered in full in his JazzProfiles.com profile, later joined the group. Mainieri was a pioneer of the "synth-vibe," an early electronic vibraphone. Steps Ahead's catalog includes Steps Ahead (1983), Modern Times (1984), Magnetic (1986), N.Y.C. (1989), Yin-Yang (1992), Vibe (1994), and Steppin' Out (2016), alongside live releases including Smokin' in the Pit (1980) and Paradox (1982).

Mainieri's role as bandleader and synth-vibe pioneer in Steps Ahead, assembling one of jazz fusion's most consistently star-studded lineups across four decades, made him one of the genre's central organizing figures, bridging traditional vibraphone technique with early electronic instrument innovation.