Bessent said the US is prepared to purchase Argentina's US dollar-denominated bonds and will do so as conditions warrant.
The US is also set to deliver significant standby credit via the Exchange Stabilisation Fund, he said.
"Argentina has the tools to defeat speculators, including those who seek to destabilise Argentina's markets for political objectives," he said in a post on X.
"I will be watching developments closely and the Treasury remains fully prepared to do what is necessary."
Bessent, a former hedge fund executive, also said the US is ready to purchase secondary or primary government debt and is working with the Argentine government to end the tax holiday for commodity producers converting foreign exchange.
He said numerous US companies had told him they intended to "make substantial foreign direct investments" in multiple Argentine sectors "in the event of a positive election outcome," but gave no details.
Argentina votes on October 26 for legislative midterm elections, in which President Javier Milei's right-wing party aims to gain seats to strengthen its minority position.
Argentine assets rose sharply on Wednesday after Bessent provided details on his previous pledge to support Latin America's third-largest economy and Milei, a close ally of President Donald Trump.
The nation's embattled peso currency has strengthened this week in a sharp reversal from last week, when the Argentine central bank burned through more than $US1 billion of reserves to defend its currency.
Markets grew panicked after Milei's party suffered a larger-than-expected loss in a local election in Buenos Aires, reflecting growing frustration with austerity measures and triggering concern over the future of Milei's reform agenda.
Trump on Tuesday said he would support Argentina but did not think it needed a bailout.
The head of the International Monetary Fund, Kristalina Georgieva, said after meeting Milei on Wednesday in New York that it is very important for Argentina to stay the course on economic reforms.
She said support like the one offered from Treasury "strengthens the program" between the IMF and the grains exporter. Argentina is due to pay the IMF $US4.8 billion next year.
In an interview on Fox Business Network, Bessent underscored US support for Argentina and Milei, adding that he did not think the market had lost confidence in the Argentine leader, but was remembering earlier crises.
"We are not going to let a disequilibrium in the market ... cause a backup in his substantial economic reforms," Bessent told the network's "Mornings with Maria" program.
"I think the market is looking in the rear-view mirror and is looking at decades, if not a century, of terrible Argentinian mismanagement.
"People are skittish. It's very hard to believe that it is different this time, but I believe with President Milei it is."
Milei, who met with Trump and Bessent on Tuesday, thanked the US for its support.
"Thank you President Donald Trump and Mr. Secretary Scott Bessent for your firm support and confidence in the Argentine people," he said in response on X.
"We value deeply our friendship with the United States and your commitment to strengthen our partnership on the basis of shared values. Together we will build a path of stability, prosperity, and freedom. MAGA!"
