The submission of a united candidate list, headed by jailed intifada leader Marwan Barghuti, marked Fatah's bid to overcome deep divisions that saw the faction initially register two rival lists for the January 25 polls.
Only after lengthy talks did the two strands of the party agree to merge the line-ups, fearful that they would otherwise see their decade-long grip of power slip away at the expense of Islamic militant group Hamas, contesting its first legislative polls.
Fatah earlier this week won legal approval for the registrations process to be reopened for a six-hour period today.
"The Future list is no more and the movement has a single list," outgoing civil affairs minister Mohammed Dahlan said at the election commission's Ramallah headquarters.
Dahlan's name had been on the alternative list of candidates which had been known as the Future but he said he was confident that a united Fatah would be victorious.
"I urge all my brothers in Fatah to cast their votes and fight for every vote in their towns and villages to ensure victory for the movement," Dahlan said.
He said that a victory for Hamas would be "a long road to perdition and obscurity".
The Middle East peace quartet of the United States, Russia, the European Union and the United Nations issued a statement apparently snubbing Hamas's political ambitions, at least under its current ideology of calling for the destruction of Israel.
"A future Palestinian Authority Cabinet should include no member who has not committed to the principles of Israel's right to exist in peace and security and an unequivocal end to violence and terrorism," it said.
Palestinian leader Mahmoud Abbas welcomed the unification of the lists.
"It is important for us to contest the electoral battle united, but also that all the other movements participate in a spirit of fair play, transparency and fairness," he said.
Blamed for years of corruption within the Palestinian Authority, Fatah has been weakened by a credible threat from Hamas which swept to victory at a series of municipal elections in Gaza and West Bank earlier this year.
Aside from an armed wing responsible for the majority of attacks on Israel during the five-year intifada, Hamas has a well-oiled political wing and bankrolls social welfare projects in areas rife with unemployment.
The Fatah-dominated Palestinian Authority has also proved largely incapable of clamping down on pervasive insecurity in the territories.
Dozens of masked gunmen from the Al-Aqsa Martyrs Brigades, a radical Fatah offshoot, earlier traded fire with police at an electoral office in Gaza City and dozens more occupied and surrounded registration offices elsewhere in Gaza.
Electoral offices were later declared re-open after gunmen ended their siege that left at least one policeman wounded, said a senior electoral commission source.
Al-Aqsa activists stormed electoral offices in the southern town of Khan Yunis and Deir el-Balah in central Gaza, as well as surrounding another in the impoverished southern border town of Rafah.