Nushi was born to Albanian Orthodox parents in Vuno, a village on the coast of Himara. He attended a grammar school in his youth. In 1928 he became an emigrant with his father for reasons of economic difficulties at home, settling in Lyons, France, where he worked as a factory laborer. In these conditions he involved himself in left-wing activity among émigré Albanian intellectuals and in 1935 became a member of the French Communist Party. In response to the Italian invasion of Albania in 1939 he returned to the country a year later, where he became a founding member of the Communist Party of Albania and played an active role in the partisan resistance during World War II. He headed the Party organization of Tirana throughout this period, using his prior experience among the French working class to organize Albanian workers and youth for the resistance, and was intermittently arrested and released by the occupation authorities in the process. He later served in political positions within the First, Second and Fourth Combat Divisions.