On Saturday, the group selected Ahmad Assi Jarba to lead the coalition.
Jarba, who is seen as close to Saudi Arabia, obtained 55 votes in the deeply divided foreign-based opposition.
He edged out the group's secretary general Mustafa al-Sabbagh, who obtained 52 votes in the second round of balloting at the group's meeting in the Turkish city of Istanbul.
The group had been with no one at the helm since the departure in May of Ahmad Moaz al-Khatib.
The selection of a new chief had initially been mooted for the end of May but had been postponed amid conflicting views on the future direction of the coalition.
In a short statement published after his appointment, Jarba said his "priority is to manage developments on the ground in Syria, particularly at Homs".
Born in 1969 in the northeastern city of Qamishli, on the border with Turkey, Jarba is a Sunni Muslim whose work for the opposition involved convincing Arab and Western nations to arm insurgents in Syria.
Meanwhile on the ground, Syrian government forces seized several buildings on the edges of militant-held districts of Homs as they pressed an eight-day operation on the central Syrian city.
Syria's state news agency SANA said the army captured several buildings in Bab Hud in the city center.