He was a professor in the University of Constantinople during World War I, when he was an officer in the German army stationed in Turkey. When he was there, he studied the spoken dialects of Arabic and Aramaic in Syria and Palestine. One of his most well known works is the 29th (and final) edition of Wilhelm Gesenius' Hebrew Grammar (1918-1929), which remained incomplete, containing only phonology and morphology of the verb. Also widely used is his Introduction to the Semitic Languages (1928). These last two works are unsurpassed in their fields, and it was with these that he gained international fame as a scholar. His last position was professor of the Semitic languages in the University of Munich.
Bergsträsser mostly engaged in the study of Arabic, focusing on the history of the text of the Qur'an. Bergsträsser left many of his planned works unfinished (including the rest of his Hebrew grammar and his grammar of spoken Aramaic), when he disappeared while mountaineering in 1933.
Bergsträsser was an outspoken anti-Nazi, and helped to save German Jewish scholars.