The US Department of Agriculture (USDA) said a wild mink had tested positive around an infected mink farm in Utah.
Coronavirus outbreaks at fur farms in the US and in Europe have killed thousands of the animals.
As a consequence, millions of farmed mink have had to be culled across Europe.
The USDA said it had found one positive case in “free-ranging, wild mink” in Utah as part of wildlife surveillance around infected farms.
Several animals from different wildlife species were sampled and all tested negative, the agency added.
It said it had notified the World Organisation for Animal Health, but there is no evidence the virus has been widespread in wild populations around infected mink farms.
“To our knowledge, this is the first free-ranging, native wild animal confirmed with Sars-CoV-2,” the USDA said in an alert to the International Society for Infectious Diseases .
The discovery raises concerns that the infection could spread between wild mink, said Dr Dan Horton, a veterinary expert at the University of Surrey, UK.
The case “reinforces the need to undertake surveillance in wildlife and remain vigilant”, he added.
Mink are known to escape from mink farms and become established in the wild. In the UK, a population of mink that escaped from fur farms many years ago is thought to exist, but they are sparsely distributed and rarely come into contact with people, Dr Horton added.
The virus has also been found in zoo tigers, lions and snow leopards in the US, and in a small number of household cats and dogs.
