Aoun, 81, a Maronite Christian and a former member of parliament, won the support of 83 members of parliament out of the necessary 65 needed to win. In Lebanon's sectarian power-sharing system, a Maronite Christian was due the seat of the presidency.
The vote on Monday was the 46th attempt to elect a president. Aoun will be the 13th president of Lebanon since the country's independence from France in 1943.
Lebanon has been dealing with a political crisis amid Syria's half-decade civil war, which has led to more than 1 million Syrians entering Lebanon, seeing refuge. The refugee crisis has divided Lebanese politics, particularly over support of Syrian President Bashar al-Assad.