The results of the poll are likely to lead to the first Shia-dominated government in an Arab state in more than 1000 years.
The United Iraqi Alliance (UIA) mustered less than half of the overall votes (48.1%) in the 30 January polls but won 140 of parliament's 275 seats due to an elimination mechanism that favours high-scoring lists.
However, the winning list falls short of the two-thirds majority needed for major decisions and looks likely to seek alliances with the Kurds, whose main electoral ticket also made a strong showing with 75 seats.
Present interim Prime Minister Iyad Allawi's group won 40 seats in the election.
The interim Iraqi vice-president
is tipped to be the next PM
The Kurds won almost 26% of the votes while Allawi's party secured about 14%.
Thursday's announcement marked the end of this stage of the election process, but the electoral commission is expected to remain in place for the next elections which are to be held in December.
The new parliament will be tasked with drafting a permanent constitution by 15 August.
Carlos Valenzuela, the chief UN election adviser, described the elections as "an immense success" and voiced his hope that the poorly represented Sunni minority would be included in the next phase of political transition.
Even as the final distribution of seats was announced, heavyweights from the winning Shia list jockeyed for cabinet portfolios and the premiership, which remained up for grabs despite earlier expectations it would go to interim Vice-President Ibrahim al-Jafari.
A meeting of UIA candidates in the capital failed to agree on a candidate for the top job, with the decision now expected next week.
"Next week will be decisive and the meeting will be held on Monday or Tuesday," said al-Jafari aide Nuri Kamal Muhammad.
Although al-Jafari's main challenger, Finance Minister Abd al-Mahdi, had reportedly dropped out of the race, former Pentagon favourite Ahmad Chalabi insisted he was still a candidate for the country's top job.