The Star Wars: Republic Commando soundtrack was composed by the LucasArts music editor and composer Jesse Harlin. The soundtrack was available as a free download on the game's official website until LucasArts took the site down. The music took on a high-paced, gritty and vocal theme to the traditional Star Wars score, bringing in several new themes and motifs unique to the Republic Commando game. The new military clone theme was based on a minor third motif from The Emperor's Theme and accompanied by the lyrics in the ancient Mandalorian language, invented by Jesse Harlin. It was the first appearance of the Mando'a, later developed into a fully working language by Karen Traviss.
The game music featured not only the original score, but also some John Williams' themes, most notably the Droid Invasion Theme, as well as some remixes of John Williams' work. For instance, the final mission on Kashyyyk featured the revised Escape from Naboo theme, with heavy male choir (also widely present in the original soundtrack) and the Prosecutor turbolift scene featured a short piano remix of The Imperial March as an easter egg.