Iran's English-language channel Press-TV quoted the Interior Ministry Election Headquarters as saying 30 reformist candidates also won seats in the Majlis in Friday's vote.
The election was for constituencies in which no parties gained over 70% in last month's first round, in which the conservatives also won a majority of votes for the 290-seat parliament.
Many of the newly-elected conservatives have openly criticized the president, Mahmoud Ahmadinejad, over his recent cabinet reshuffle, as well as his failure to bring inflation under control.
Some are also unhappy about his aggressive foreign policy stance, which has alienated the country from the West.
In Friday's polls, the conservatives won 10 seats in the capital, Tehran, leaving just one seat to a reformist. The faction says many of its candidates were blocked from participating, and has called the vote neither free nor fair.
