From 1932 to 1939, Niitov worked as a private singing teacher and music instructor, as well as the voice director of the Tartu Men's Singing Society [et] choir and, at the invitation of Gustav Ernesaks, also of the Tallinn Men's Choir. Among the students in his voice studio were Andrei Christiansen, Jaan Haabjärv [et], Naan Põld [et], and Eino Uuli [et].[3] He also sang at the Vanemuine Theater[3] and taught singing at the Põlva Public Education Society [et], where he served as chairman of the board.
From 1935 to 1939, Arno Niitov taught at the Valga Music School [et], the Tallinn Pedagogical Institute, and the Tallinn Normal School [et]. From 1940 to 1941, he was the head of the voice department at the Tallinn Conservatory.
In 1944 he moved to Germany and from there to Austria, and in 1952 to Canada.[3] In Montreal he conducted the Estonian male choir, and he also worked as an apartment building office manager, a farmer, a restaurant owner, and a high school Latin teacher.[3] In 1955, he was targeted by the Committee on Return to Homeland (a.k.a. the Mihakailov [ru] Committee),[7] a "redefection" campaign that sought to persuade political exiles to relocate to the USSR.[8]
Niitov died in Montreal in 1989, a few weeks short of his 85th birthday.[3] He is buried in Mount Royal Cemetery in Monteal.