Moussa, a 10-year Mubarak-era foreign minister and 10-year Arab League secretary-general who ran for president of Egypt after Hosni Mubarak's 2011 ouster, defeated influential lawyer Sameh Ashour to lead the 50-person Constitution-drafting committee, the officials said.
The vote by committee members was 30 for Moussa and 16 for Ashour, with two abstentions and two members absent, they said.
Ashour had the support of the revolutionary grassroots Tamarod youth movement, which helped spur the massive nationwide protests that led to Morsi's July 3 ouster by the military, the privately owned Egyptian newspaper al-Masry al-Youm reported.
Moussa said he ran for the post after consulting various political powers, the newspaper said.
Moussa heads the anti-Islamist National Salvation Front with ex-U.N. nuclear watchdog chief Mohamed ElBaradei and leftist Hamdeen Sabbahi.
The military-backed committee, which includes only two Islamists, will now determine the number of deputy heads, al-Masry al-Youm said.
The amended charter is to be approved by Oct. 7, or within 60 days of the committee's first meeting, which was Sunday.
The revised Constitution, with Islamic articles removed, will then be put to a popular vote, followed by envisaged parliamentary and presidential elections early next year and a promised return to civilian rule.
The changes are part of a political "road map," or "constitutional declaration," by interim President Adly Mansour, installed by the army after it overthrew Morsi.
The Constitution being revised was signed into law by Morsi Dec. 26 after it passed with 64 percent support in a popular referendum Dec. 15-22 that had only a 33 percent turnout.
It replaced 2011's provisional Constitution, adopted after the Egyptian revolution that ousted Mubarak Feb. 11, 2011.
The Egyptian army suspended the Islamist Constitution July 3, the day of Morsi's ouster.