Ant, backed by Jack Ma, billionaire founder of e-commerce platform Alibaba, was set to sell shares worth about $34.4bn (£26.5bn) on Thursday.
The listing in Shanghai and Hong Kong would have been the biggest stock market debut to date.
But Chinese authorities have cited "major issues" as the reason behind the eleventh hour suspension.
Ant runs Alipay, the main online payment system in China, which has eclipsed cash, cheques and credit cards.
Alibaba, which owns a third of Ant, saw it share price plunge 9.6% in Hong Kong trading on Wednesday.
This followed a 8.1% fall in New York on Tuesday after the suspension was announced.
This wiped nearly $76bn off Alibaba's value, more than double the amount Ant was planning to raise.
The Shanghai Stock Exchange said in a statement that Mr Ma had been called in for "supervisory interviews".
A change to the regulatory environment meant Ant no longer met "listing conditions or information disclosure requirements".
The Hong Kong exchange then reported that Ant had decided to suspend its planned listing.
Ant was due to sell about 11% of its shares across the two stock exchanges. But the pricing valued the whole business at about $313bn.
The previous largest debut was Saudi Aramco's $29.4bn float last December.
What was meant to be the world's biggest initial public offering has now been squashed by Chinese regulators.
In his prospectus letter, Ant's executive chairman, Eric Jing, had waxed lyrical about how the company is revolutionising the future of money.
Perhaps what he and Jack Ma - the billionaire founder of Alibaba and the largest controlling shareholder in Ant - didn't factor in is how ultimately, no matter revolutionary your business is, if it's operating in China, it still needs the blessing of Chinese regulators.
The firm's executives and Mr Ma were called in by Chinese authorities ostensibly for a discussion on regulating the sprawling fintech firm.
But media reports indicate the meeting may have also been an opportunity to address comments Mr Ma made at a fintech conference last month.
Mr Ma compared traditional banks to "pawn shops", lauding the merits of the digital banking system instead.
He said future lending decisions should be based on data, not collateral.
That is likely to have set off alarm bells for Chinese officials.
Ant collects vast amounts of data from its customers - data that the Chinese government doesn't have immediate access to, unless it asks for it.
China is extremely supportive of Chinese companies. It's a criticism levelled at it by other countries.
But in return, Beijing also expects a degree of control over Chinese companies that you wouldn't normally see in other countries.
Jack Ma's digital empire is increasingly veering outside that circle of control. Suspending this listing may serve as reminder of who really calls the shots.
Presentational grey line
"Ant Group sincerely apologises to you for any inconvenience caused by this development," the company said in a message to investors.
"We will properly handle the follow-up matters in accordance with applicable regulations of the two stock exchanges."
