Activists have called for a boycott of what they describe as "farce" elections, raising doubts about the credibility of the polls. The government says the elections are democratic.
The polls opened at 8am local time (05:00 GMT) and are set to close at 8pm (17:00 GMT).
Bahrain's Al Khalifa regime has kept a lid on dissent since the Shia opposition staged an uprising in 2011. Saudi Arabia sent in troops to help crush the unrest in a mark of concern that any power-sharing concession by Bahrain could inspire Saudi Arabia's own Shia minority.
Bahrain, which is home to the US Navy's Fifth Fleet, has closed the main opposition groups, barred their members from running in elections and prosecuted scores of people, many described by human rights groups as activists, in mass trials.
"Clearly, legislatures from the world's leading democratic states believe that the upcoming election in Bahrain lacks legitimacy. You simply cannot crush, torture and imprison your entire opposition, call for a pseudo-election, and then demand the respect of the international community," said Sayed Ahmed Alwadaei, director of the UK-based Bahrain Institute for Rights and Democracy (BIRD), according to Al Jazeera.
The government said 506 candidates are running in the election, including the highest number of female candidates. It expects a higher voter turnout than in 2014, which it put at 53 percent, when opposition groups boycotted the elections.
Only 23, out of 40 incumbents of the House of Representatives, are seeking re-election this year to parliament, which has limited powers.
Many of Bahrain's Shia say they are deprived of jobs and government services and treated as second-class citizens in the country of 1.5 million.
Human Rights Watch said in a statement that Manama is failing to create conditions necessary for a free election by "jailing or silencing people who challenge the ruling family" and banning all opposition parties.
A leader of dissolved opposition group al-Wefaq said the rise of Saudi Crown Prince Mohammad bin Salman, also known as MBS, has emboldened Bahrain's authorities in their crackdown on dissent, which has included stripping scores of activists from their nationality.
"They couldn't go ahead with all the crackdown without the strong backing of the Saudi government. Mohammad bin Salman listens only to hardliners in Bahrain's ruling family," Ali Alaswad, who lives in self-exile in London and has been sentenced in absentia to life in prison, told Reuters news agency.