Born in 1903 in Odessa in the Russian Empire. Immigrated to Eretz Israel as a pioneer and worked on roadmaking. Completed Haganah courses with honors. In 1925 was appointed deputy commander of Jerusalem District, Haganah, and in 1929-1931 served as District Commander.

The 1929 riots caused unrest in the Haganah ranks because the organization was not ready and did not respond appropriately to the Arab attacks. The disputes on this issue led to Tehomi's departure from the Haganah, and the establishment of the Irgun Zvai Leumi which he headed. Tehomi tried to unite the two organizations and in 1937 returned to the Haganah in order to take up a senior position. When the Haganah failed to fulfil its obligations under the amalgamation agreement, Tehomi resigned, and from then on engaged in independent illegal immigration activities and intelligence work. Several years later he retired from all activity. In the last few years of his life, he lived in the United States.