Japan's conservative Liberal Democratic Party (LDP) has surged back to power just three years after a devastating defeat.
The win gives giving ex-prime minister Shinzo Abe a chance to push his security agenda and radical economic strategy.
Television exit polls showed the LDP winning nearly 300 seats in parliament's powerful 480-member lower house.
Its ally, the small New Komeito party looked set to win about 30 seats.
That would give the two parties the two-thirds majority needed to over-rule parliament's upper house, where no party has a majority and which can block bills, which should help to break a deadlock that has plagued the world's third biggest economy since 2007.
An LDP win will usher in a government committed to a tough stance in a territorial row with China, a pro-nuclear energy policy despite last year's Fukushima disaster and a potentially risky prescription for hyper-easy monetary policy and big fiscal spending to beat deflation and tame a strong yen.
Senior executives of the LDP and the New Komeito party met earlier to confirm they would form a coalition if they get a combined majority, Kyodo news agency reported.
Voters had expressed disappointment with Prime Minister Yoshihiko Noda's Democratic Party of Japan (DPJ), which swept to power in 2009 promising to pay more heed to consumers than companies and reduce bureaucrats' control over policymaking.
Public broadcaster NHK quoted a party executive as saying that Mr Noda is likely to quit as leader of the DPJ.
Exit polls showed the DPJ, which was hit by defections ahead of the vote, winning only 65 seats, just over a fifth of their tally in 2009.
Many voters had said the DPJ failed to meet its election pledges as it struggled to govern and cope with last year's huge earthquake, tsunami and nuclear disaster, and then pushed through an unpopular sales tax increase with LDP help.
