Harmony was founded in 1892 by Wilhelm Schultz in Chicago, Illinois, growing to become the largest musical instrument manufacturer in the United States during the mid-20th century. Between 1945 and 1975, the company produced an estimated ten million guitars, peaking in 1964–1965 with annual sales of 350,000 instruments per year. The Chicago-era catalog spanned acoustic and electric guitars, ukuleles, banjos, and violins, sold both under the Harmony name and through major retailers like Sears. Notable vintage models include the Stratotone solid-body electric family — introduced in 1952, predating the Fender Stratocaster name by two years — the Sovereign H-1260 flat-top acoustic, and a long-running series of Roy Smeck signature models dating back to 1928.

Artists who played Harmony instruments during the company's original run include Ritchie Valens, whose primary guitar was a Harmony H44, and Buck Owens, who had a signature red-white-and-blue H169 model. Elvis Presley, Howlin' Wolf, and members of The Rolling Stones also played Harmony guitars. The original company closed in 1975 following mounting competition from lower-cost imports.

The Harmony name was revived in 2018 under BandLab Technologies, which manufactures new instruments at the historic 225 Parsons Street facility in Kalamazoo, Michigan — the former Gibson factory now shared with Heritage Guitars, another BandLab subsidiary. The modern lineup consists of American-made electric guitars including the Silhouette, Rebel, Jupiter, Juno, and Comet, drawing on vintage Harmony design cues while incorporating contemporary construction. Harmony also produces amplifiers and accessories.

Harmony has 123 products cataloged on Equipboard, including Solid Body Electric Guitars, Semi-Hollowbody Electric Guitars, and Steel-string Acoustic Guitars. Their gear is featured by 215 artists, with the strongest followings in Rock, Folk, World, & Country, and Pop. Notable users include Dan Auerbach, Ryan Adams, and Jack White. Harmony's catalog spans the full price spectrum — from entry-level options to high-end flagships.