The song was originally released as a single in early 1980 by Seafood Mama, Quarterflash's predecessor band. It featured more sparse instrumentation but a more dramatic vocal arrangement than the hit version and was a regional success on radio stations in Portland, Oregon. The record's video features theatrics in and around an office trailer with dark corridors and swinging light bulbs from the ceiling before it was bulldozed and torched.
After changing their name, Quarterflash released their self-titled debut album in 1981 which contained the new version of "Harden My Heart". This version was released as the album's first single. In early 1982, it reached #3 on the Billboard Hot 100 and also hit #1 on the BillboardHot Mainstream Rock Tracks chart. The song also reached the Top 20 in Germany, in New Zealand and in France, though it stalled below the Top 40 in the United Kingdom. It was the group's only Top 10 Pop single, although their follow-up single from the album, "Find Another Fool", and their 1983 hit "Take Me to Heart" both entered the Top 20. This song is included in the game Grand Theft Auto: Vice City Stories, in the radio station Emotion 98.3 and was played twice in the pilot episode of Knight Rider. It also appears in the game Activision Anthology.