Meanwhile, Markevitch had begun to conduct, debuting on the podium with the Amsterdam Concertgebouw Orchestra in 1930. He studied conducting with Hermann Scherchen in 1935. His composing activities dropped off as he increased his conducting. He spent World War II in Italy, having acquired Italian citizenship. In 1944 he was appointed music director of the Maggio Musicale Orchestra in Florence. He began conducting full time, coming into demand as a guest conductor, and held a variety of directorships or principal conducting appointments with the Stockholm Symphony Orchestra (1952-1955), the Montreal Symphony Orchestra (1956-1960), the Havana Philharmonic Orchestra (1957-1958), the Concerts Lamoureux of Paris (1957-1961), the Spanish Radio and Television Orchestra (1965-1969), the Monte Carlo Orchestra (1967), and the orchestra of the Accademia di Santa Cecilia in Rome (1967-1972). His American debut was with the Boston Symphony Orchestra in 1955. He also began giving conducting master classes, especially in Monte Carlo, from 1969.
He was known for his performance of the Russian repertory and twentieth century music. He had a quick temper, reflected in his music in sharp emotional shifts, yet the music was meticulously prepared and nearly always followed the composer's directions with exceptional care. In the late '90s, his recordings came back into demand in re-release, and even his compositions were finding a small but interested market and were praised anew for their originality.