Born in Tschoschl, Czechoslovakia, Hanell, who originally wanted to become a teacher of ancient languages, took private music lessons with H. Zitterbart in Teplice, where he worked as répétiteur and choir conductor from 1943.
In 1944 he became musical director in Meiningen and held the same position from 1945 to 1948 at the Zwickauer Theater and from 1948 to 1950 at the Bühnen der Stadt Gera [de].
In 1952 Hanell became municipal music director in Görlitz, before he was appointed first Kapellmeister at the Komische Oper Berlin by Walter Felsenstein in 1955.
Guest appearances have taken him to Munich, Hanover, Frankfurt, Prague and Warsaw.
On 2 September 1981, Hanell was awarded the Goethe Prize of the City of Berlin for his work as principal conductor of the Großes Rundfunkorchester Berlin and as permanent guest conductor of the Staatsoper.