[citation needed] Warnow was born in Monastyrishche, Kiev Governorate, Russian Empire to Jewish parents; he immigrated with them to the United States in 1907.

On July 2, 1935, a CBS program debuted with singer Virginia Verrill starring and Warnow's orchestra accompanying her.

A 1941 newspaper article described Warnow as "the busiest man in radio", noting that his conducting duties included not only Your Hit Parade, but Helen Hayes Theatre and We, the People.

Mark Warnow also conducted the orchestra for the "Sound Off" Radio show, 1946, New York City, sponsored by the U.S. Army to encourage post World War II recruitment.

Emcee Arno Tanney, aka "The Chant" would sing/chant army recruiting commercials like a drill seargeant in his signature booming baritone to the rapid fire rhythm of the "Duckworth Chant" - "Join the Army, it's for you, better pay and college too, Sound Off!, 1, 2, Sound Off!

[citation needed] In the 1940s, Warnow conducted and arranged for Frank Sinatra while the singer was signed to Columbia Records, then owned by the CBS network.