The sister of Thailand's exiled former prime minister has promised to do her best in government after leading his supporters to a landslide election win.
Yingluck Shinawatra said there was "a lot of hard work ahead", after preliminary results showed Pheu Thai had won a clear majority in parliament.
With nearly all votes counted, Pheu Thai had 264 seats and Prime Minister Abhisit Vejjajiva's Democrats 160.
Ms Yingluck's elder brother, Thaksin, was deposed in a military coup in 2006.
Both parties campaigned for an end to the divisions which have plagued Thailand since and caused deadly clashes between their followers.
Last year, protesters shut down parts of Bangkok for two months in a bid to force Mr Abhisit's government to resign. When the army stepped in to clear the streets it degenerated into violence, leaving 91 people dead.'Victory of the people'
The results of Sunday's election pave the way for Ms Yingluck, a 44-year-old business executive, to become Thailand's first female prime minister and the fifth person to hold the post since her brother.
"I don't want to say that Pheu Thai wins today. It's a victory of the people," she told a crowd of supporters outside her party's headquarters after receiving a call of congratulations from her billionaire brother.
She said she was discussing a coalition with the smaller Chart Thai Pattana and other parties.
"I would like to reiterate that we are ready to deliver on all of the policies that we have announced. There is a lot of hard work ahead."
"I'll do my best and will not disappoint you."
Prime Minister Abhisit - who has dismissed Ms Yingluck as her brother's clone and noted that her party's slogan is "Thaksin Thinks, Pheu Thai Acts" - said his opponent had the right to form a government.
"The outcome is clear. Pheu Thai has won the election and the Democrats are defeated," he said.
"I will give the chance to Yingluck, the first woman to form a government," he added. "I want to see unity and reconciliation. The Democrats are ready to be in opposition."
Both parties promised to raise the minimum wage; improve transport connections to the north; make healthcare more widely available and affordable; and continue to fund microfinance schemes in rural areas.
In an interview with the BBC World Service from Dubai, where he lives to avoid a prison sentence for corruption that he says was politically motivated, Mr Thaksin said it was clear the Thai people had voted for change.
"They want to see reconciliation, we want to have reconciliation," he said, adding that all parties would have to respect the voters' decision.
Mr Thaksin said the military should also "be listening to what the people think".
Asked whether he would now be returning to Thailand, possibly through an amnesty for all political crimes committed since 2006, Mr Thaksin insisted that he was in "no hurry".
"I want to see reconciliation really happen," he said. "I want to be part of the solution, not part of the problem."
The BBC's Rachel Harvey in Bangkok says Mr Thaksin's return would almost certainly be unacceptable to the army generals who removed him from power five years ago.
It is unclear whether this election will mark a new start, a chance to leave the bitterness and bloodshed behind, or test Thailand's fragile democracy once more, our correspondent adds.