He was a star in Abraham Goldfaden's first Bucharest-based theater troupe — and the playwright wrote the title role of "Shmendrik" for him. Mogulesko soon founded his own troupe and dominated Yiddish theatre in Romania for a decade. After immigrating to the United States, he eventually founded the Rumanian Opera House on New York City's Lower East Side, one of the great venues of Yiddish theater. The "Jewish Encyclopedia" described him in 1904 as "the best comedian on the Yiddish stage… He is known also as a leading composer of music for the Yiddish stage."