Hezbollah and its allies have won all the parliament seats for South Lebanon, where elections were held on Sunday.
South Lebanon has a large Shia Muslim population
Interior Minister Hassan Sabei said the alliance - which included Amal, another armed Shia Muslim movement - won by a wide margin all 17 contested seats.
Hezbollah's victory sends a message of defiance to the US and Israel, which view it as a terrorist group.
The alliance won all 17 contested seats, in addition to six seats where there had been no challengers.
The two anti-Israeli, pro-Syrian groups won more than 80% of the votes. Turnout was 45%, officials said.
On the ticket were two Maronite candidates, two Greek Catholics, a Greek Orthodox and a Druze, as well as 14 Shia Muslims and three Sunnis.
This combination conforms to the complicated confession system of allocating seats in Lebanon, with MPs divided equally between Christians and Muslims.
Backing for arms
Correspondents say electoral support for Hezbollah is being seen as a vote against US interference and for its militia to remain armed despite a UN resolution issued last year.
Security Council resolution 1559 demanded the withdrawal of all non-Lebanese (ie Syrian) forces and the disarmament of militias - a clear reference to Hezbollah and Palestinian guerrillas.
Last Sunday, anti-Syrian candidates won all 19 seats in elections in Beirut.
Hezbollah was credited with ousting the Israeli army from southern Lebanon in 2000, after 22 years of occupation.
It is estimated that it has between 500 to 1,500 militiamen under arms in Lebanon, and has vowed to keep fighting until Israel withdraws from a disputed area on the border.