[1] Martienssen was a younger son of his parents,[2] attended the Domschule Güstrow and received his first music education in theory, organ and piano from Johannes Schondorf in his home town.
[3] After the Abitur Martienssen studied musical composition with Wilhelm Berger, musicology with Hermann Kretzschmar and piano playing with the Liszt student Karl Klindworth in Berlin, and at the Leipzig Conservatory (today Hochschule für Musik "Hanns Eisler").
[6][7] After the Second World War, Martienssen was professor at the Musikhochschule in Rostock from 1946 to 1950, before he was appointed to the State Conservatory in East Berlin in 1950 (today Hochschule für Musik "Hanns Eisler").
In 1912 - this is emphasized in renowned music encyclopedias - he was able to rediscover in Copenhagen the until then lost cantata by Johann Sebastian Bach Mein Herze schwimmt im Blut (BWV 199).
Among his students were the composers Hugo Distler, Georg Trexler, Artur Immisch and Hans Schaeuble, the conductors Sergiu Celibidache and Adolf Fritz Guhl, the pianists Karl-Heinz Schlüter, Carl Seemann, Max Martin Stein, Sebastian Peschko, Erik Then-Bergh and Viktorie Svihlikova, as well as the organists and church choirmaster Thomas-Kantor Kurt Thomas (St. Thomas Church Leipzig), Kreuz-Kantor Herbert Collum (Dresden Church of the Holy Cross), Robert Köbler (University Church Leipzig), Käte van Tricht (Bremen Cathedral), the long-time choral director of the Deutsche Staatsoper Berlin Ernst Stoy and numerous renowned music teachers such as August Leopolder, Ottilie Fröschle and Kurt Hessenberg.