It is being described as a blow to Iran’s conservative Islamic establishment.
Final results after elections on Friday show that allies of the reformist President Hassan Rouhani have made big gains.
They have won all of the 30 parliamentary seats up for grabs in the capital and 15 out of the 16 Tehran seats in the so-called Assembly of Experts, ousting two prominent conservatives including the speaker.
Elias Hazrati, a newly-elected reformist deputy, told euronews: “Even though a big majority of well-known reformers were not able to stand or were disqualified, they’ve shown that they’re flexible and able to adapt to the situation and propose new faces.
“People had a good memory of the reformist period and Mr. Khatami, and they’ve expressed their confidence in the whole reformist movement.”
Commentators say the results could mean Iran will further its new ties with the West after the recent nuclear deal that resulted in sanctions being lifted.
However, despite the gains by Rouhani and his allies, the conservatives remain in power overall due to the two-tier system of clerical and republican rule.
Euronews correspondent Javad Montazeri reported: “We can say the result is a victory for the reformers and the moderates.
“As well as supporting the policies of Rouhani’s government, the new parliament can also embark on economic and political reforms and open up even further relations with Western countries and attract investment in Iran.”