Despite only around half of voters casting a ballot, the conservative Abe claimed popular endorsement for his mix of nationalism and "Abenomics" -- a signature plan to fix the country's flaccid economy that enjoyed early success but faded into a recession.
"The ruling coalition has been given a majority," Abe told a television interviewer. "We humbly want to meet the public's expectations.
"I think we received people's mandate for the Abe government's performance in the past two years. But we must not be complacent and must carefully explain to the public when implementing policies," Abe told TBS.
TV Asahi said the pairing had won 333 of the 475 seats, while TBS put the figure at 328.
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Washington was among the first to welcome Abe's victory, hailing his "strong leadership on a wide range of regional and global issues" from Ebola to the fight against the Islamic State group.
"The US-Japan alliance is the cornerstone of peace and prosperity in the Asia-Pacific," White House spokesman Josh Earnest said in a statement.
The first two of his "three arrows" of Abenomics -- monetary easing and fiscal stimulus -- have largely hit their targets; the once-painfully high yen has plunged, giving exporters a boost, and stocks have rocketed.
Prices have also begun rising after years of treading water -- proof, says Abe, that this is the beginning of a virtuous circle of economic growth, with higher wages soon to follow.
However a sales tax rise in April snuffed out consumer spending, sending Japan into the two negative quarters of growth that make a recession.