The concerned Minnesota resident was an adult male, had a recent travel history to New York City, and had been fully vaccinated. He developed mild symptoms on Nov 22 and sought COVID-19 testing on Nov 24, the state's health department said, adding that his symptoms have resolved.
The United States reported its first case of the omicron variant in California on Wednesday.
The administration of US President Joe Biden is urging all eligible Americans to get vaccines and boosters to fight omicron, which is spreading quickly around the world, and will increase family vaccination sites and expand availability at pharmacies.
Just 58.9 percent of the total US population, or 196 million people, have been fully vaccinated, one of the lowest rates among wealthy nations.
More than 786,000 people have died from COVID-19 in the United States, including 37,000 in November alone.