After more than three months with no local cases, a 57-year-old retired Vietnamese man in the central city of Da Nang tested positive for the virus.
Following the discovery, authorities announced on Sunday that they had found three more infections.
In response, the Vietnam Professional Football (VPF) announced all domestic football leagues have been suspended.
The country’s top Vleague and the First Division were supposed to play new rounds starting July 29.
The change in plans is “to ensure the safety of the players”, organisers said in a statement.
No details were provided on when the matches might resume.
Vietnam has won praise for its handling of the virus, registering just 420 infections Sunday and no deaths as of late Sunday despite sharing a long border with China.
Authorities responded quickly after the virus emerged in neighbouring China, with a rigorous state quarantine and contact-tracing system put in place.
