The album, which included the Top 40 hit "Burnin' for You" (#1 on Billboard's Album Rock Tracks chart) represented a resurgence of the group's commercial standing after two albums with disappointing sales. Fire of Unknown Origin would be the final studio LP featuring the band's original lineup until 1988's Imaginos; during the subsequent tour, the band fired original drummer Albert Bouchard.
The album continues BÖC's tendency to write quirky songs, from the title track (featuring lyrics by Patti Smith) to "Joan Crawford". Many of the songs were intended for the soundtrack of the animated film Heavy Metal, such as "Vengeance (The Pact)", whose lyrics follow in detail the plot of the "Taarna" segment of the movie. However, only the song "Veteran of the Psychic Wars" (which, ironically, was not written for Heavy Metal), co-written by science fiction author Michael Moorcock, ended up in the film's final version and soundtrack.