In 1899, together with tenor Leonid Sobinov and bass Feodor Chaliapin, he toured Russian cities conducting opera.
He conducted in many venues in Russia, Western Europe and the United States subsequently.
He also conducted Rimsky-Korsakov's Kashchey the Immortal in January 1917 at the Bolshoi Theatre in Moscow.
He emigrated to the West in 1924, and was a long-time staff conductor at the Metropolitan Opera in New York.
From 1944 until his death in 1960, Cooper conducted for Pauline Donalda's Opera Guild of Montreal.