Chadema says the three bills do not address concerns over the last presidential election in 2020, which former authoritarian leader John Magufuli won by a landslide despite opposition claims of fraud.
But the government of President Samia Suluhu Hassan, who took over after Magufuli died in 2021, insists the reforms will improve democracy in the East African nation.
Thousands of people joined a demonstration last week organized by Chadema, which had urged the government to withdraw the bills, calling for greater independence for the electoral commission.
Lawmakers began debating the bills on Tuesday before voting on the legislation on Friday.
"We have done our job by approving the bills... We will now send the bills to the President for assenting into laws," said parliament speaker Tulia Ackson.
Chadema has focused its criticism on a measure that would allow Hassan to directly appoint five of the 10 members of the electoral commission ahead of a presidential election next year.
The demonstration organized last week by the opposition party was held in the financial capital Dar es Salaam. It was the biggest since the government lifted a ban on opposition political rallies a year ago.
"We have not seen any change after the first protest in Dar es Salaam. Instead, the government ignored our demands and moved ahead with debating the contentious bills," Chadema secretary general John Mnyika told reporters on Thursday.
Chadema leader Freeman Mbowe, who has spent time in prison under both leaders, has said the bills offer only "cosmetic" reforms.
The party has announced a round of weekly protests this month in the cities of Mwanza, Mbeya and Arusha, starting on February 13.
Parliament is dominated by the ruling Chama Cha Mapinduzi, CCM party which has 364 out of the 392 seats.
Hassan has sought to reverse some of the more hardline policies of her predecessor, whose strongman tendencies earned him the nickname "Bulldozer".
A ban on opposition gatherings was overturned in January 2023.
Shortly afterwards, one of Tanzania’s most prominent opposition leaders, Tundu Lissu, returned to the country after having spent most of the previous five years in exile.
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