Grünberger, who was baptized as Johannes Paul and later changed his religious name to Theodor, was a native of Bettbrunn, which at that time belonged to the Upper Palatinate. At the Augustinian monastery there, he perfected his organ playing skills after initial instruction from his father, and soon after entered the monastic organ service as an Augustinian. Here he was also ordained a priest. As can be seen from many of his cheerful compositions, Grünberger must have been full of joie de vivre. A joie de vivre that was perhaps lived too intensively for the Augustinian monastery (he had fallen in love), which is why he was then emphatically felt to be superfluous. However, through the intervention of the sovereign, who was extremely taken with his music, he was graciously readmitted - albeit punitively transferred. In later years, too, his stay in various monasteries in southern Germany is documented. However, due to recurring tensions, he finally had himself transferred to the secular priesthood at his own request. In 1803, he found a significant field of work for six years as a professor of organ and singing at the Bavarian State Teachers' Seminary in Munich. After that he lived for a short time as a private teacher in Salzburg. He died at the age of 64 as a highly esteemed and sought-after musician (at the end very withdrawn in Moosburg in Upper Bavaria). In addition to organ and other handwritten compositions for mass celebrations as well as for sacred occasions (choral as well as instrumental) sonatas for violin and keyboard instrument were known and sought after throughout his life.
