The polls will take place under a new constitution passed by lawmakers in September 2015 as part of a peace process that began with the end of a decade-long civil war in 2006.
The war pitted the Maoists against the state and left more than 16,000 people dead.
After Maoist rebels gave up their arms, they joined the parliamentary system, resulting in Nepal shifting from a monarchy to a secular federal republic.
In 2015, the country enacted a constitution seeking to empower marginalised communities, including women and Dalits - the so-called untouchables - by ensuring greater representation in state institutions.
The polls are a major step toward implementing the new constitution.
“The election is key to taking Nepal out of the long-going transitional phase and to enter yet another significant chapter of state restructuring as per the new constitution,” Bishnu Sapkota, a political commentator, said.
More than 90 parties have fielded candidates, but the polls are expected to be most tightly contested between the ruling Nepali Congress and a two-faction communist alliance of the Unified Marxist-Leninists (UML) and the Maoists.
More than 6,000 candidates are vying for 275 seats in the new federal parliament and 550 seats in seven provincial assemblies across the country.
The top leaders in the three major parties have staged election rallies across the country, with candidates travelling door-to-door to win votes.
As part of standard security operations, the government has deployed half a million officers, including army, police and civil servants, to oversee the elections at some 20,000 polling centres.
Fears of violence have increased, however, after a series of explosions targeted
candidates.
Early last week, Sher Dhan Rai, a former information minister and UML candidate, narrowly escaped a crude bomb hurled at his jeep when he was on his way to a rally in eastern Nepal.
Over the weekend, dozens of explosions across the country targeted candidates including former deputy prime ministers and former ministers fielded by the three political parties.
No candidates have been hurt, but the violent incidents left more than a dozen people
injured.
Police have arrested more than 200 anti-poll protesters belonging to the Communist party of Nepal, a splinter Maoist group, but the group has not claimed responsibility for the attacks.
“We have instructed security agencies to crack down on anti-poll activities and take action against those involved,” Narayan Prasad Sharma Duwadi, a home ministry spokesman said in a statement.
A majority of Nepal’s 15.4mn registered voters are expected to turn out for the election.
The second phase of the polls is scheduled for December 7 in the capital Kathmandu and the low-lying areas in the south.
The political parties have promised stability and economic growth in Nepal, which has faced a series of disasters in recent years, including a powerful earthquake in 2015 and devastating floods in the southern plains this past summer.
Bishnu Sapkota, a political commentator, said the political parties’ election manifestos lack a real agenda.
“They talk about prosperity and stability - almost all of them - but that is abstract,” Sapkota said, adding, “They have not defined what that means or how they will achieve it.”
Traditional parties are likely to get the lion’s share of the votes, but an upstart party of urban, Western-educated young professionals is challenging the old guard.
Rabindra Mishra, a former bureau chief in the BBC Nepali service, has been fielded by the anti-corruption Bibeksheel Sajha Party in a coveted Kathmandu constituency against Prakash Man Singh, former deputy prime minister in the ruling party.
But political observers say the newcomers have a long way to go.
“They have some appeal to educated youths in the urban areas,” Sapkota said. “But I don’t think they will do very well because Nepali society is still traditional.”
