The Muslim Brotherhood's Mohammed Mursi has been declared the winner of Egypt's presidential election with 51.7% of the vote.
At a press conference Mr Mursi said that he will be a "president for all Egyptians."
He also said that he would preserve all international treaties and charters.
He succeeds Hosni Mubarak, who was overthrown 16 months ago after a popular uprising.
However, the military council has curbed the powers of the presidency, meaning the head of state will have to work closely with the army on a planned democratic constitution.
Thousands of Brotherhood supporters burst into cheers on Cairo's Tahrir Square, waving national flags and chanting "Allahu Akbar!" or God is Great, greeting a dramatic victory.
Mr Mursi, 60, is an engineer who trained in a US university. He spent time in jail under Mr Mubarak.
He won the first round ballot in May with a little under a quarter of the vote.
He has pledged to form an inclusive government to appeal to the many Egyptians, including a large Christian minority, who are anxious over religious rule.
The two candidates, Mr Mursi and former prime minister Ahmed Shafiq, had appealed the results.
Muslim Brotherhood supporters demonstrated in central Cairo overnight ahead of the result.
Elsewhere, Israel voiced respect for the victory of the Muslim Brotherhood.
Israel has called on the new administration in Cairo to maintain the countries' peace accord.