Sadr's alliance, which contested Iraq's parliamentary elections for the first time, gained 54 parliamentary seats, the commission announced on Saturday.
The Moqtada al-Sadr movement, forms the backbone of the Sa'iroun alliance, which also includes the communists, but the senior Shia cleric himself, who enjoys a strong support, did not contest the elections.
The Conquest Alliance, led by former transport minister and secretary general of Badr Organisation, Hadi al-Ameri, came in second, winning 47 seats in the parliament, and the Victory Alliance, headed by incumbent Prime Minister Haider al- Abadi, came in third, winning 42 seats.
The Conquest Alliance is a new alliance that contested the election for the first time. It consists of 18 political parties many of which are former factions of the Popular Mobilization Units (PMU). The PMU, more commonly known by its Arabic name as Hashd al-Sha’abi, was key in defeating Daesh terrorists last year. The main units have handed over their weapons to the state in order to participate in the political process.
Iraqis voted last Saturday in the first national elections since the country declared complete victory over Daesh terrorists.
The electoral commission of Iraq announced that 44.5 percent of those eligible had cast their ballots in the elections.
Over 7,000 candidates contested the 329 seats in the parliament that will determine a new president, a new prime minister and a new government in Iraq.
This is the fourth such poll since the 2003 US invasion of the country, that led to a sharp rise in sectarian tensions, violence, and acts of terrorism.
Analysts say the next prime minster will face huge challenges, such as rebuilding a country shattered by years of war against foreign-backed Daesh terrorists , as well as years of occupation by US military forces.
Western-created and Western-trained Daesh terrorists unleashed a campaign of death and destruction in Iraq in 2014, overrunning vast swathes in lightning attacks. Iraqi army soldiers and allied fighters then launched operations to eliminate the terrorist group, and reclaim lost territory.