[1] He joined the Jewish Agency, and became a board member, serving as director of its economics department between 1946 and 1948.

[1] Bernstein was one of the people to sign Israel's declaration of independence on 14 May 1948, and was appointed Minister of Trade and Industry in the provisional government.

Re-elected in 1951, he returned to the cabinet as Minister of Trade and Industry in the fourth and fifth governments.

[2][3] Bernstein also stood as a candidate in the Knesset's election for president in 1952, but withdrew after the second round of voting, having come a distant second to eventual winner Yitzhak Ben-Zvi.

He was re-elected to the Knesset later that year and oversaw the alliance with Menachem Begin's Herut to form Gahal.