A longtime ally of Shinzo Abe, Yoshihide Suga had been predicted as the frontrunner in the lead-up to the ruling Liberal Democratic Party’s (LDP) leadership election.
Suga, 71, who has said he will pursue Abe's key economic and foreign policies, won 377 votes out of 534 votes cast, and 535 possible votes, in the Liberal Democratic Party (LDP) election by the party's members of parliament and representatives of its 47 local chapters.
Rival Shigeru Ishiba, a former Defense Minister, won 68 votes and ex-foreign minister Fumio Kishida got 89.
Suga is virtually certain to be elected prime minister in a parliamentary vote on Wednesday because of the LDP's majority in the lower house.
He will serve out Abe's term as party leader through September 2021. Suga thanked Abe and vowed to push ahead with reforms.
Shinzo Abe, Japan's longest-serving premier, said last month that he would resign because of ill health, ending nearly eight years in office.
"I was born as the oldest son of a farmer in Akita," Suga said. "Without any knowledge or blood ties, I launched into the world of politics, starting from zero — and have been able to become leader of the LDP, with all its traditions and history."
"I will devote all of myself to work for Japan and its citizens," he added.
Suga has said he would continue Abe's signature "Abenomics" strategy of hyper-easy monetary policy, government spending and reforms while juggling the problems of Covid-19 and a slumping economy, and confronting longer-term issues such as Japan's aging population and low birth rate.
Japanese manufacturers remained pessimistic for a 14th straight month in September, a Reuters poll showed, underlining the huge challenge the next leader faces.
Yoshihide Suga, whose resume is thin on diplomatic experience, faces geopolitical challenges such as building ties with the winner of the November 3 US presidential election and balancing concern over China's maritime aggressiveness with bilateral economic interdependence.
Speculation is simmering that Suga will call a snap election for parliament's lower house as soon as next month to boost his chances of winning a full three-year term as LDP chief next year.
A vote for the lower chamber must be held by late October 2021.