Authorities expect some 600,000 eligible voters -- slightly more than half of the 1.1 million population -- to put their names down for the legislative elections, expected by October.
But the country's opposition and unions have rubbished the vote as undemocratic and a mere rubber-stamping of the autocratic rule of King Mswati III.
"We call on people not to register but if they can't ... we call on them to peacefully disrupt the vote," said Kenneth Kunene, secretary general of the Communist Party of Swaziland (CPS), one of the leading opposition parties.
Kunene, in exile in South Africa, alleged that police had been deployed to "intimidate" and coerce people to register to vote.
Candidates in the election are shortlisted in their chiefdoms, whose leaders are directly appointed by the king.
Political parties have been banned in Swaziland and last month at least three activists were arrested and charged with sedition during protests against the king's rule.
Tensions have been running high especially since April 12, which marked the 40th anniversary of a royal decree that transformed Swaziland from a democracy into an absolute monarchy.
The People's United Democratic Movement (PUDEMO) said the parliamentary elections wont bring any change to the poverty-stricken and landlocked country wedged between Mozambique and South Africa.
"Who has the power in Swaziland? The power rests with the king, no matter what you do. You can't do anything if it doesn't please the king," said Sikhumbuzo Phakathi, PUDEMO's general secretary.
"It shows how useless the parliament is in Swaziland," added the general secretary.
The voter listing process was launched just under a week after South Africa's African National Congress (ANC), the ruling party in the regional powerhouse, made a rare call for democracy in Swaziland.
The ANC also demanded that political prisoners being held in the country be freed and exiles be allowed to return.
Percy Simelane, a Swaziland government spokesman, scoffed at the ANC's calls for reforms.
"We are a democratic country, we are following our national constitution because what is in the constitution is the sentiment of people in Swaziland."
"We cannot take orders from outside because the future of this country is in the hands of the Swazi people, not in the hands of neighbours or political parties," said Simelane.
King Mswati III has faced sustained criticism of his autocratic rule, fuelled by high levels of poverty.
But Simelane said if Swazis want the country to move to a multiparty system, they will have to express that desire through constitutional amendments, inferring that no such demands have been made.
The voters elect their candidates "freely", he said. "We do not impose the candidates on the electorates."
Despite the political woes, Swaziland is culturally rich and remains a cheap tourist destination still attracting thousands of visitors each year.
"The monarch has succeeded in presenting itself as a holiday destination ... a nice tourism and leisure place where you can take part in the reed dance while hiding the misery of the population," said Kunene.
Reed dance is an annual Swazi tradition where tens of thousands of bare-breasted virgin girls dance before the ruling King Mswati III. The flamboyant king who already has 13 wives normally chooses a wife during the ceremony.