The former military leader was elected last month with 96 percent of the vote. In inauguration ceremonies in Cairo, al-Sisi lauded outgoing President Adly Mansour, despite years of political turmoil in the country and the overthrow of prior President Mohamed Morsi in a July 2013 military coup.
"In the long history that goes back thousands of years, our homeland did not witness democratic transfer of power. Now, for the first time, the President-elect shakes hands with the outgoing President, and together they sign a power transfer document in an unprecedented occasion," al-Sisi said in his inaugural address Sunday.
His election sparked an energetic celebration in Cairo's Tahrir Square, although the White House questioned "the restrictive political environment in which this election took place."