The Southern District Health Board advised of the case in a release shortly before 9pm
The SDHB said the person was in Dunedin, Wanaka, and Cromwell during their infectious period.
The board said locations of interest would be published on the Ministry of Health website when they were identified.
"If you live in, or have visited, the Dunedin, Wanaka or Cromwell area recently please check this list. It is updated regularly.
"The SDHB asks anyone with cold or flu like symptoms, no matter how mild, to get tested for COVID-19 and isolate at home until a negative test result is returned.
"The most common early symptoms of the Omicron variant is a sore or scratchy throat, and a runny nose. If you have these symptoms, please get tested as soon as possible."
The release said the Dunedin case was isolating at home, and the variant had not been confirmed.
The case will be counted in tomorrow's Ministry of Health case numbers, as will the two cases confirmed earlier today in Queenstown.
The SDHB said an investigation into the source of the Dunedin case was ongoing.
Testing locations
Testing is available throughout the Southern district.
However, people should call their GP first or Southern Health on 0800 847 8719.
There is regional specific information about general practices offering testing on the WellSouth website.
Walk-in and drive-through testing is also available at the following sites:
Dunedin Covid Community Testing Centre
Drive-through/walk in - no appointment required, 11am to 7pm, seven days a week. 5 Malcolm St, Dunedin
Te Kāika Testing Centre
Drive-through/walk-in - no appointment required, 9am to 4pm, seven days a week, Victoria Rd (car park next to the ice rink)
