Mirziyoev has promised reforms since becoming president in 2016 after the death of his predecessor, the authoritarian Islam Karimov, who ruled the Central Asian nation for nearly three decades.
However, analysts say the 20 million eligible voters in Uzbekistan will again face a limited choice.
The five political parties running in the parliamentary elections are all represented in the current body, long viewed as a rubber-stamp institution.
Mirziyoev has urged lawmakers to take a greater role in policymaking. The elections are being held under the slogan “New Uzbekistan, New Elections.”
The Liberal Democratic Party of Uzbekistan (LDPU) currently holds 52 seats, the most in the 150-seat Oliy Majlis, the lower house of parliament. Next is Milli Tiklanish (National Revival party) with 36.
Mirziyoev has released more than 50 high-profile political prisoners since coming to power, but there are still unknown numbers locked away.
And despite legislation outlawing it, there are continued reports of torture in Uzbekistan’s prisons.
The Organization for Security and Cooperation in Europe (OSCE), which is sending an observer mission to the polls, has said many features of past votes remain in place.
The legal process for registering new parties remains “burdensome and open to arbitrary application,” the OSCE said in an interim report released on December 13.
It said the election campaign did not meet international standards. “Very few campaign posters are visible.”
“So far, very little evidence of outdoor campaign activities has been observed,” the report said.
The party with some of the boldest promises is Milli Tiklanish, which opposes Uzbekistan’s potential entry into a trade bloc led by ally Russia and wants to replace Prime Minister Abdula Aripov with its own candidate.
But Milli Tiklanish backs Mirziyoev’s reform agenda, just like all the other four parties.
Uzbekistan’s political evolution “will need time,” the party’s chairman Alisher Kadyrov told AFP. “Our problems did not appear yesterday but over a number of years.”
Though no genuine opposition parties are registered to compete, there will be a new party running in these elections: the Ecological Movement of Uzbekistan (OEH), which was registered in January.
However, the new party has already stirred controversy, with reports of some “members” being forced to join. It has also backed plans to build a nuclear power plant in Uzbekistan, prompting some commentators to say it is the only “green” party in the world to support atomic energy.