[1][2][3] Paul Sepp was born at Orava Manor [et] in the former Orava Parish,[3] the son of Gustav Friedrich Müller (1852–?)
He studied at the town school in Pskov until 1899, and at the private theater school of Yuri Yuryev [ru] in Saint Petersburg from 1906 to 1907.
[3] Sepp worked as an actor in Russia, but during his military service from 1908 to 1910 he lost his voice and then devoted himself to stage management.
[4] In 1920, together with the publisher Peter Leoke, Sepp founded the private Drama Studio Theater School [et] in Tallinn in 1921 and worked there intermittently until 1933, when the school closed due to financial difficulties.
[7] From 1932 to 1940, he operated his own private theater studio, and from 1938 to 1941 he was a lecturer at the Tallinn Conservatory's National School of Performing Arts.