Property developer Truong My Lan, 68, was convicted earlier this year of embezzling money from Saigon Commercial Bank (SCB) -- which prosecutors said she controlled -- and condemned to die for fraud totalling $27 billion.
In her official handwritten appeal of more than five pages seen by AFP, Lan said that the death sentence was "too severe and harsh", asking the court to consider a more "lenient and humane approach".
Tens of thousands of people who had invested their savings in SCB lost money, shocking the communist nation and prompting rare protests from the victims.
According to Vietnamese law, Lan could escape the death penalty if she proactively returns three-quarters of the embezzled assets and is judged to have co-operated sufficiently with authorities.
But prosecutors have argued that she has not met the conditions, and emphasised her crime's consequences were "huge and without precedent".
Lan, who founded real estate development group Van Thinh Phat, told the court in Ho Chi Minh City that "the quickest way" to repay the stolen funds would be "to liquidate SCB, and sell our assets to repay SBV and the people".
"I feel pained due to the waste of national resources," Lan said last week, adding she felt "very embarrassed to be charged with this crime".
Lan owned just five percent of shares in SCB on paper, but at her trial the court concluded that she effectively controlled more than 90 percent through family, friends and staff.
The State Bank said in April that it pumped funds into SCB to stabilise it, without revealing how much.
Among the assets that Lan and Van Thinh Phat own are a shopping mall, a harbour and luxurious housing complexes in business hub Ho Chi Minh City.
During her first trial in April, Lan was found guilty of embezzling $12.5 billion, but prosecutors said the total damages caused by the scam amounted to $27 billion -- equivalent to around six percent of the country's 2023 GDP.
Lan and dozens of defendants, including senior central bank officials were arrested as part of a national corruption crackdown dubbed the "burning furnace" that has swept up numerous officials and members of Vietnam's business elite.
A total of 47 other defendants have requested reduced sentences at the appeal.
Last month, Lan was convicted of money laundering and jailed for life in a separate case.
