He volunteered for the Jewish Legion of the British Army during World War I and then joined the group which founded Kibbutz Degania Bet, combining manual labor with political activism. He was among the founders of the Histadrut - General Federation of Labor, where he became involved in labor issues and later in the promotion of cooperative agricultural development.

In 1937 Levi Eshkol played a central role in the establishment of the Mekorot Water Company and in this role was instrumental in convincing the German government to allow Jews emigrating to Palestine to take with them some of their assets - mostly in the form of German-made equipment. He served as Mekorot's managing director until 1951, introducing a system of countrywide water management which made intensive irrigated farming possible. His endeavor culminated in the ambitious National Water Carrier project, which became operative in 1964, during Eshkol's tenure as Prime Minister.

A member of the Haganah high command, he engaged in arms acquisition prior to and during the War of Independence and in 1950-51 served as Director-General of the Ministry of Defense, where he laid the foundations for Israel's defense industries.

In 1951 Eshkol was appointed Minister of Agriculture and Development, and from 1952 to 1963 - a decade characterized by unprecedented economic growth despite the burden of financing immigrant absorption and the 1956 Sinai Campaign - he served as Minister of Finance. Between 1949 and 1963, Eshkol also served as head of the settlement division of the Jewish Agency. In the first four years of statehood, he was also treasurer of the Jewish Agency, largely responsible for obtaining the funds for the country's development, absorption of the massive waves of immigrants and equipment for the army.

When Ben-Gurion retired from politics in 1963, Levi Eshkol - with experience as a Haganah member and a cabinet minister - succeeded him as both Prime Minister and Minister of Defense.

In 1964, Eshkol made the first state visit of an Israeli Prime Minister to Washington, laying the foundation for the close rapport that has existed between the two countries ever since, and in 1966 he visited six African nations. But his most significant diplomatic achievement was the establishment of diplomatic relations with West Germany, a process which had been initiated by Ben-Gurion. He also secured military assistance from Germany, underscoring Germany's moral commitment to supporting Israel.

A master of internal politics, Eshkol succeeded in forming the "Alignment" (a merger of rival Labor factions) and leading his party to victory in the 1965 elections. In 1964, in a conciliatory gesture, he also ordered that the remains of Labor's fiercest political rival - Ze'ev Jabotinsky, founder and ideological leader of the Revisionist movement - be brought to Israel and re-interred in a state funeral on Mount Herzl in Jerusalem. Thus, Eshkol honored Jabotinsky's last will, written in 1935, requesting that his remains be transferred to Israel "only on the instruction of a future Jewish government."

The 1967 Six-Day War, with its stunning military victory, was undoubtedly the highlight of Eshkol's six years as Prime Minister. In the tension-filled days prior to the outbreak of war, Eshkol appointed retired General Moshe Dayan as Minister of Defense. He then formed Israel's first national unity government, which included opposition leader Menachem Begin. After the war, Eshkol's diplomatic efforts succeeded in obtaining sophisticated American weaponry, including advanced aircraft, for the IDF, a change from the situation in the 1950s when almost all the IDF's weaponry was bought in Europe. After the Six-Day War, he initiated talks with Palestinian leaders in the administered areas, in an effort to promote a neighborly relationship, and ultimately, peace.

Levi Eshkol died in office in February 1969 of a heart attack, at the age of 73.