After graduating from high school, he did his national service in the Israel Defense Forces in the Intelligence Corps, reaching the rank of Lieutenant.

Shortly before entering politics, he tried and failed to buy control of El Al, Israel's national airline.

[8] On 27 May 2016, he submitted his resignation from the government in protest at the appointment of Avigdor Lieberman as Minister of Defense and the coalition's shift to the right.

[14] Following Herzog's resignation in July 2018, Tzipi Livni took over the post and following the dissolution of the Zionist Union, former Labor chief Shelly Yachimovich succeeded her.

[17] In his political plan, published during the 2017 Labor leadership primaries,[18] Gabbay expressed support for a two-state solution, with the Palestinian state being demilitarized and the settlement blocs and Jordan Valley remaining under Israeli control.

The IDF would be deployed along the Jordan River until the conflict is resolved, maintaining Israeli freedom of action in the West Bank.

[23] In January 2018, he declared that if the negotiations with the Palestinians will fail, a unilateral disengagement should be carried out, and that such a plan does not necessarily require the evacuation of settlements.

[24] According to the social-economic plan he published during the 2017 Labor leadership primaries, Gabbay supports an increase in expenditure on social benefits and services along with public sector efficiency measures.

Gabbay supports the expansion of the social networks protecting all employees, and is in favor of linking wages to the Consumer Price Index.

According to his plan, an equitable taxation system must be created in order to deal with the trends of inequality and deep gaps in Israeli society; in order to reduce the cost of living in Israel, he proposed that there should be an increase in market competition, a reduction in bureaucracy and competition among kosher agencies should be created.

[25] Gabbay stated support for public transportation on Shabbat,[26] as well as allowing supermarkets and hang-out places to remain open on Shabbat,[27] Reform conversions,[28] Civil marriage,[29] the Western Wall compromise, and against the "Hadata" (הדתה, "religionization") of schools by the activities of the various associations (Amutot)[30] On the issue of enlisting Ultra orthodox Haredim, on the other hand, he declared that this was unrealistic.

"[36] Gabbay condemned Morawiecki's words: "The blood of millions of Jews cries from the earth of Poland over the distortion of history and the escape from blame.

The government of Israel has to be a voice for the millions of murdered and strongly denounce the Polish prime minister's words.