Abdel-Fattah al-Sisi, Egypt's former defense minister, was sworn in Sunday by the Supreme Constitutional Court as the country's new president after winning last month's presidential poll.
"I swear to uphold the republican system and respect the constitution and the law," said Sisi, taking the oath of office.
The new president was sworn in by members of the Supreme Constitutional Court.
Outgoing interim President Adly Mansour, who now returns to his old post as head of the Supreme Constitutional Court, stood beside Sisi.
Al-Sisi, who had resigned his post as army chief to contest the presidential poll, has been officially declared Egypt's new president after winning almost 97 percent of the vote, according to Egypt's election commission.
The vote was the second milestone of a transitional roadmap imposed by the army after its ouster of elected president Mohammad Morsi on July 3 following mass protests against his one-year rule.
With the swearing-in ceremony concluded, Sisi starts a four-year presidential term.
Apart from public activities expected to be held across the country to celebrate the inauguration of a new president, Sisi will attend two major activities later Sunday in Cairo.
The new president will host a reception in honor of Arab and foreign dignitaries attending his inauguration, including Lebanon's Speaker Nabih Berri.
Later in the evening, a special celebration will be organized by the presidency for Egyptian dignitaries.
Sisi is expected to deliver during the celebration his first official national address outlining his priorities as president.
Egypt's state television said it would broadcast both events live.
Sisi starts his tenure while this populous Arab country faces several economic, political and security challenges.
