The prolonged dry spell, which has already been declared a national disaster, would also hit food production and was likely to affect the mining sector, Hichilema said in a live television address to the nation.
Zambia is Africa's second-largest copper producer.
Hichilema said the energy sector this year was expected to have a deficit close to 450 megawatts or even above 500 megawatts.
The 2024 national budget will be re-aligned so that more resources could be channeled towards addressing the impact of the drought, Hichilema said.
"The current projections are that over a million farming households will be affected," he said, adding that the drought had destroyed about 1 million hectares of the 2.2 million planted crop.
Zambia defaulted three years ago and is trying to rework its debt under the G20 Common Framework, a programme designed to ensure swift and smooth debt overhauls for low-income nations.
Hichilema said Zambia's situation was dire and called on its official and private creditors to quickly conclude its debt restructuring process.
"If this process does not close, it's not just an indictment on Zambia but the global system," Hichilema said.
Hichilema also called on multilateral development agencies and donor countries to assist Zambia with humanitarian support such as food. Britain, the United Nations and the World Bank were among those that had already committed to assist Zambia, he said.
(Reporting by Chris Mfula; Editing by Anait Miridzhanian and Christina Fincher)
