"My return is planned for next Wednesday," Moussa told reporters at Beirut airport on Saturday.
"I am coming back because the situation remains dangerous."
Officials from both the ruling Western-backed majority and the Hezbollah-led opposition had predicted yet another postponement because of the continued standoff between the two sides.
"Efforts and consultations with Lebanese political figures... and the Arab and international parties continues," Moussa said. "A lot of details, and even key issues, still have to be discussed."
Asked if Syria was an obstacle to a deal, he said: "No, you cannot say that, really... On the Arab initiative, I think its role is positive, and we will carry on our contacts with Syria and Saudi Arabia."
The initiative from the Arab League is based on a three-point plan calling for the election of General Michel Suleiman, the current army chief, as president, a national unity government in which no one party has veto power and adopting a new electoral law.
Although the ruling coalition has given the Arab plan its full support, Hezbollah is insisting that the opposition have a third of the seats in a new 30-member government in order to have veto power.
Hassan Fadlallah, a Hezbollah MP said the US, which along with Saudi Arabia backs the government of Fouad Siniora, the prime minister, was raising "a veto each time we come near a deal."
The Arab League plan calls for the governing majority to hold 14 seats in the new cabinet, the opposition 10 seats and Suleiman would be able to pick six ministers, making him the arbiter in any contested decisions.