R. Henkin was born in Klimovichi, Belorussia, where his father was head of the yeshiva. Leaving his native town, he studied for six years at the yeshiva of Slutsk under R. Isser-Zalman Meltzer, who together with R. Baruch Baer Leibowitz and R. Jechiel Michael Epstein ordained him. After serving as rabbi in Kavkazskaya and as head of the yeshivah in Sokolov, Henkin emigrated to the United States in 1922 and settled in New York City. In 1925 he was appointed director of Ezras Torah, an organization founded in 1915 by the Union of Orthodox Rabbis to provide assistance to rabbinical scholars in war-torn Europe. Under his direction, Ezras Torah expanded into a general charity distributing hundreds of thousands of dollars annually to thousands of needy persons. Henkin was continually called upon to decide points of Jewish law. He was particularly authoritative on divorce procedure and on laws of Sabbath as they relate to the new technology.