Netanyahu said he would apply "Israeli sovereignty over the Jordan Valley and northern Dead Sea," the BBC reported.
Such a move would be popular with right-wing parties which he would have to depend on to form a coalition but fiercely opposed by Palestin.
Arab nations, including officials in Jordan, Turkey and Saudi Arabia, have heavily condemned Netanyahu's annexation plans.
The Arab League denounced "the dangerous development" as "aggression".
Palestinian diplomat Saeb Erekat said such a move would be a "war crime" that would "bury any chance of peace".
Israel occupied the West Bank, along with East Jerusalem, Gaza and the Syrian Golan Heights, in the 1967 Middle East war.
It effectively annexed East Jerusalem in 1980, and the Golan Heights in 1981, although neither move was accepted internationally for decades.
The Donald Trump administration has since recognised both steps, overturning previous US policy.
Palestin claim the whole of the West Bank for a future independent state. Netanyahu has insisted that Israel would always retain a presence in the Jordan Valley for security purposes.
The fate of the West Bank goes to the heart of the Israeli-Palestinian conflict. Israel has built about 140 settlements there and in East Jerusalem which are considered illegal under international law, though Israel disputes this.
More than 600,000 Jews live in the settlements, which the Palestin want removed.
( With inputs from IANS )