Anutin set the stage for the snap election in mid-December, amid a raging border conflict between Thailand and Cambodia, in what analysts said was a move timed by the conservative leader to cash in on surging nationalism.
It is a gamble that paid off for a prime minister, who - having taken over after Paetongtarn Shinawatra of the populist Pheu Thai Party was ousted over the Cambodian crisis - then dissolved parliament less than 100 days later.
"Bhumjaithai's victory today is a victory for all Thais, whether you voted for Bhumjaithai Party or not," Anutin told a press briefing.
"We have to do the utmost to serve the Thai people to our full ability."
With more than 90 per cent of polling stations reporting, preliminary results released by the election commission showed the Bhumjaithai Party with a sizeable lead over the progressive People's Party in second place, followed by the once-dominant Pheu Thai Party.
When Anutin dissolved parliament in December, he cited dysfunction and infighting between rival parties as making it impossible to lead a minority government.
While the Bhumjaithai Party was unlikely to win a majority outright, the results suggest it is in a strong position to push through campaign pledges, said Napon Jatusripitak, a political scientist at the Bangkok-based Thailand Future think-tank.
Those include implementing a consumer subsidy program and ditching an agreement with Cambodia over maritime claims.
"For the first time in a long time, we will likely have a government that has sufficient effective power to govern," he said.
"We are seeing what I would describe as a marriage of convenience between technocrats, conservative elites and traditional politicians."
Critical to Anutin's success were his embrace of nationalism and Bhumjaithai's strategy of winning over politicians from rival parties in rural areas, analysts said.
"The scale of its victory was unanticipated, perhaps demonstrating that the more nationalist political environment and its ability to consolidate the conservative electorate all worked in its favour," political analyst Mathis Lohatepanont said.
Speaking even as results were trickling in, People's Party leader Natthaphong Rueangpanyawut conceded that, while some votes had yet to be counted, his party did not look likely to win.
Natthaphong said the party would not join a Bhumjaithai-led government but would also not form a competing coalition.
"If Bhumjaithai can form a government, then we have to be the opposition," he told a press conference.
The progressive People's Party, with its message of structural change and reforms to the economy, had led most opinion polls during the campaign.
But in a survey conducted during the campaign's final week and released on Sunday, the National Institute for Development Administration projected that Bhumjaithai would be the winner with between 140 and 150 seats in the 500-member House of Representatives, ahead of 125-135 for the People's Party.
The People's Party is the successor to the Move Forward Party, which won the most House seats in 2023 but was blocked from forming a government by conservative MPs and then forced to dissolve.
Thai voters were also asked on Sunday to decide if a new constitution should replace a 2017 charter, a military-backed document that critics say concentrated power in undemocratic institutions, including a powerful senate that is chosen through an indirect selection process with limited public participation.
The election commission's early count showed voters backing the referendum by a margin of nearly two to one.
Thailand has had 20 constitutions since the end of absolute monarchy in 1932, with most of the changes following military coups.
If voters back the drafting of a new national charter, the new government and lawmakers can start the amendment process in parliament with two more referendums required to adopt a new constitution.
with AP
