Mansour was sworn in Thursday at the Constitutional Court in a ceremony aired live on Al Arabiya television.
According to military decree, Mansour will serve as the country’s transitional president until a new leader is elected.
The swearing-in ceremony came a day after the Egyptian military ousted former Islamist President Mohammad Mursi who refused to resign and insisted on his legitimacy as an elected civilian president.
The armed forces acted to remove Mursi after millions of Egyptians demonstrated for four days against rule.
Mursi is under house arrest at an undisclosed location.
“I swear to preserve the system of the republic, and respect the constitution and law, and guard the people’s interests,” Mansour said as he took the oath.
Officials welcomed the declaration with a warm round of applause.
Mansour went on to pay tribute to the Egyptian people, media, the military and the police force.
“A salute to the Egyptian people for correcting on June 30 the path of this glorious revolution,” he said in reference to protests that saw millions take to the streets on the anniversary of Morsi's first turbulent year in power.
The nationwide protests “proved to the world” the determination of Egyptians in the face of adversity, said Mansour.
The 67-year-old praised the armed forces for having “always been the conscience of the nation” and “not hesitating for a moment to meet the call of the nation and people”.
Mansour also described the Egyptian media as a “courageous free beacon that lit the way for the people and unveiled the misdeeds of the former regime.”
(With AFP and Reuters)
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