Electronic Musician began as Polyphony magazine in 1975, published by PAiA Electronics as a synthesizer hobbyist magazine. In 1976 it was spun off as a separate company, Polyphony Publishing Company. It was sold to Mix Publications in 1985. Mix Publications was bought by Act III Communications around 1989, which in the 1990s was bought by Primedia'. Primedia's business magazines were spun off as Prism Business Media in 2005; Prism merged with Penton Media the next year. NewBay Media bought the magazine in 2011.
Marvin Jones was the founding editor of the magazine from 1975 to 1980. Craig Anderton was editor of the magazine from 1980 to 1990.