However, Idris's authority within the country remains limited, with some of the most successful rebel groups on the ground rejecting his authority.
The Syrian government did not immediately comment on the Istanbul meeting. It blames the war on a foreign conspiracy to weaken Syria being carried out by terrorists on the ground.
Hitto did not receive a resounding mandate from the coalition, of which he is not a member. Of the group's 63 active members, only 48 voted. Four cast blank ballots and Hitto received 35 of the remaining votes.
Hitto was born in Damascus, the Syrian capital, in 1963, according to his official resume provided by the coalition. Little known in Syria, Hitto has lived in the United States for more than two decades, most recently in Texas. He has academic degrees from Purdue University in Indiana and Indiana Wesleyan University.
He worked for a number of different technology companies and helped run a Muslim private school called the Brighter Horizons Academy. He is also a founding member of the Muslim Legal Fund of America, which was founded to give legal aid to Muslims following the September 11, 2001, terrorist attacks.
He is married with four children.
Activist Ghassan Yassin, who watched the vote after traveling from the embattled city of Aleppo, said he saw "no reasons to be optimistic about the formation of an interim government."
He said he had only heard of Hitto recently and doubted his government would have the resources to make a difference.
"The question is not whether there is an interim government, but whether there will be any support for it," he said.
Syria's conflict began with political protests in March 2011, and has since spiraled into a civil war, with hundreds of rebel groups fighting Assad's forces across the country. The U.N. says more than 70,000 people have been killed and millions pushed from their homes by the violence.
Also on Monday, Assad's fighter jets struck targets near the town of Arsal, Lebanon, according to Lebanon's state-run National News Agency. The two countries share a porous border.
U.S. State Department spokeswoman Victoria Nuland confirmed that Syrian warplanes and helicopters had fired rockets into northern Lebanon, striking near Arsal.
"This constitutes a significant escalation in the violations of Lebanese sovereignty that the Syrian regime has been guilty of," Nuland said. "These kinds of violations of sovereignty are absolutely unacceptable.'
Associated Press writer Bradley S. Klapper in Washington contributed to this report.