Vietcombank sold the dollar at VND25,543, up 0.02% from the weekend. The greenback was steady at VND25,850 on the black market.
The State Bank of Vietnam raised its reference rate by 0.02% to VND24,327.
The dollar has risen against the dong by 4.6% in the year to date.
Globally, the Japanese yen traded around five-month lows on Monday against a dollar underpinned by rising U.S. yields as thin year-end liquidity kept most currencies in tight ranges, Reuters reported.
The yen was changing hands at 157.71 with only the risk of Japanese intervention preventing another test of the 160 level last seen in July.
The dollar index measure against major rivals was flat at 107.98.
The euro stood at $1.0429, not far from recent troughs and in a holding pattern in holiday trading. The currency is heading for a calendar-year drop of roughly 5.5% on the dollar.
"Despite paid forecasters almost universally calling for a weaker U.S. dollar in 2024, the greenback looks set to close the year higher against all major currencies with the buck reigning supreme," said Chris Weston, head of research at Australian online broker Pepperstone.
For the month, the dollar index is up 2.3%, bringing year-to-date gains to 6.6%.