In 1892, he became burgomaster of Berlin (vice-mayor) and advanced to its Lord Mayor (Oberbürgermeister) holding that office between 1899 and 1912.

Kirschner junior attended the universities of Freiburg, Strassburg, Zurich and Munich.

Following his promotion in Strassburg in 1904 he went to Berlin for postgraduate studies under Rudolf von Renvers (1854–1909).

He was appointed professor of surgery at Königsberg in 1916, and in 1927 accepted an invitation to move to the same chair in Tübingen.

On 18 March 1924, Kirschner performed the first successful pulmonary artery embolectomy — Trendelenburg's operation.