The former coup leader presenting himself as a rock of stability in a turbulent region pushed for constitutional changes that will extend tenure until at least 2024 in the Arab world’s largest state.
Despite protests from rights groups, the three-day plebiscite is expected to approve another six-year term for Sisi.
The referendum bucks the trend of the region’s mini-Arab Spring, in which mass pro-democracy protests this month swept away veteran presidents in Algeria and Sudan.
Sisi made his grab for power in the turbulent years after the original Arab Spring protests of 2011 toppled long-time ruler Hosni Mubarak, who was followed in office by Islamist president Mohamed Morsi.
Sisi overthrew Morsi in 2013 and the following year won his first term as president. He was re-elected in March 2018 with more than 97 per cent of the vote after standing virtually unopposed.
International observers slammed both elections while Sisi’s government has been widely criticised for sweeping repression of its opponents — both Islamists and secular groups.
Human Rights Watch charged the constitutional amendments aim to strengthen Sisi’s “authoritarian rule”, while Amnesty said that parliament, having already backed the changes, had shown a “complete disregard for human rights”.