Robert began his career as a composer of small forms. Later, the songs were joined by film scores, for which he went to Boston. From analyzing the compositions of John Williams, Bernard Herrmann, Ennio Morricone or Philip Glass, it was only a step to Stravinsky, Bartok and then to Ligeti, Gorecki, Messiaen and Scelsi.

Robert Jisa is best known for having composed ambient and electroacoustic music based around only one pitch, altered in all manners through microtonal oscillations, harmonic allusions, and changes in timbre and dynamics, as paradigmatically exemplified in his Pět tibeťanů ("Five Tibetans", 2003). Later, he explored the relation between sound frequency and human brain in concert show The Illumination Voices (2013), opera DURST (2021), concert Hourglass (2023) and upcoming music performance Amazonas.