The projections, based on exit polls, showed the ruling Liberal Democratic Party easily retaining its majority in the 475-seat House of Representatives. Exit polls have been reliable predictors of the final results in past Japanese elections.
The Liberal Democrats, a conservative party that has been in power for most of the post-World War II era, appeared to have fallen short of securing a two-thirds majority on their own, but may have done so together with their coalition partner, the Buddhist-backed Komei party.
A landslide victory could improve Abe's chances of pushing ahead with difficult political and economic reforms, and his long-term goal of revising Japan's constitution.
Abe, who took office two years ago, called Sunday's snap election last month, saying he wanted a fresh mandate for his economic revitalization program, known as Abenomics.
Share prices have risen and many companies have reported record profits, but the recovery has faltered in recent months, with the country returning to recession after a sales tax hike chilled demand among consumers and businesses.
"I believe this shows that voters gave the Abe administration a positive evaluation over the past two years," said Finance Minister Taro Aso, who retained his seat in parliament. "Abenomics is still halfway through, and I feel a strong sense of responsibility to push it further."
But the vote was seen as less of a verdict on Abe's policies than an acquiescence to the ruling party's growing power. Despite weakening popularity ratings, a recession and messy campaign finance scandals, the Liberal Democrats were virtually certain to triumph thanks to voter apathy and a weak opposition.
The popularity of the Democratic Party of Japan, which held power from 2009 to 2012, plunged after it failed to deliver on campaign pledges and struggled in the aftermath of the 2011 earthquake, tsunami and nuclear disasters.
"I think Mr. Abe is the only choice we have considering from what I heard and saw in the reports," retiree Hiroshi Yamada said as he came out of a downtown Tokyo polling station.
Two hours before polls closed, voter turnout was 35 per cent, 6.8 percentage points lower than the same time in the previous lower house election in 2012, the Internal Affairs Ministry said.
Many voters were perplexed over Abe's decision to call an election.
"I think two years is too soon to decide whether his policy failed or not," said Yoshiko Takahashi, a Tokyo businesswoman.
Associated Press writers Mari Yamaguchi, Emily Wang and Kaori Hitomi contributed to this report.