Although conservatives have the upper hand in parliament, analysts say the assembly may give Mahmoud Ahmadinejad, the president, a tougher time as his rivals manoeuvre for political positions before the 2009 presidential election.
Mostafa Pourmohammadi, the interior minister, was quoted by local radio as saying that the conservatives took more than 69 per cent of 287 seats decided, suggesting they held almost 200 seats.
Iranian media also reported that the results of three parliamentary seats were annulled for unspecified reasons.
Pourmohammadi said: "My assessment is that the future parliament will be more capable [than the last], with stronger expertise. I hope there will be stronger interaction between the government and the parliament."
The so-called reformists - whose hopes of mounting a significant challenge were dashed by mass disqualifications before the polls - appeared to have held up respectably in the second round outside Tehran.
But according to Pourmohammadi, the reformists fared badly in the run-offs in the capital, with conservatives taking 10 out of the 11 seats having already swept up all 19 of the seats available in the first round.
Reformists, considered Ahmadinejad's staunchest critics, have said the vote was unfair because the unelected Guardian Council, which tests candidates on their commitment to Islam and Iran's clerical system, barred many of them from standing.
Pressure on Ahmadinejad
But government officials say the system is fair and impartial.
Just one reformist, Ali Reza Mahjoub, was set to sit in the new parliament after squeezing into 11th place in the second round.
A conservative-controlled parliament is not expected to be wholeheartedly supportive of Ahmadinejad, who has alienated many of his fellow conservatives with controversial policies and speeches.
Ahmadinejad faces a re-election battle in the summer of 2009, against a background of discontent over high inflation.
Economists blame the president's expansionary economic policies for stoking inflation, while his attacks on opponents and frequent changes to his cabinet have also stirred controversy.