Vietnam will buy between 50 million and 150 million doses of the vaccine, according to a report in state-run newspaper Tuoi Tre.
At a government meeting on Friday morning, acting Minister of Health Nguyen Thanh Long said Vietnam had ordered the Russian-made Covid-19 vaccine.
When exactly the doses will be purchased and delivered remains unclear.
"In the meantime, Vietnam will still continue developing the country's own Covid-19 vaccine," a broadcast on the nation's state-run Vietnam Television (VTV) said on Friday, citing the Health Ministry.
Russian President Vladimir Putin announced on Tuesday the country had approved a Covid-19 vaccine named Sputnik V.
Russian officials have dismissed concern expressed by scientists around the world over the lack of final-stage testing of the vaccine.
Vietnam is aiming to have its own Covid-19 vaccine ready for human trials at the end of 2020 and ready for general use by October 2021, according to state media reports.
The South-East Asian nation has thus far been relatively successful in its response to the coronavirus pandemic and received repeated praise from the World Health Organisation (WHO).
Yet after a fresh outbreak in the coastal city of Da Nang in late July after months of no community transmissions of the virus, the number of new infections has been rising rapidly and the country has seen its first deaths linked to Covid-19.
As of Sunday morning, Vietnam has officially recorded 951 infections and 24 deaths. - dpa