In 1926 Sádlo was engaged by the Česká Filharmonie - the Czech Philharmonic Orchestra, where he was active until the autumn of 1961.
From 1933 to 1945 he was a member of the Union of Professional Musicians, and from 1931 to 1946 in the committee of the Club of Orchestral Artists in Prague.
Miloslav Sádlo organized both domestic and foreign tours, where he also played the viola.
Foreign travel was mainly before the Second World War: to Italy, Yugoslavia, England, France, Switzerland, Austria, the Netherlands, Romania, and elsewhere.
In Australia there was a concert for the local Czechoslovak community (there were a large number of Czech and Slovak emigrants after the war).