The first positive test dates back to Dec. 8, health officials said. Currently, none of the individuals with Omicron have died or had to be hospitalized.
"It was only a matter of time before the Omicron variant arrived in DuPage County," said DuPage County Health Department Executive Director Karen Ayala.
Coronavirus cases are at very high levels right now across the state, with both Omicron and still Delta dominating.
Health officials are urging residents to get vaccinated and boosted.
"We want to remind residents that we have the tools to stop the spread of these highly contagious variants. Tools such as COVID-19 vaccinations, including booster shots, wearing a high-quality face mask, maintaining 6-feet distance from others, getting tested when you have symptoms or before you gather, and increasing the flow of fresh air in indoor spaces," Ayala said.
Those looking to schedule an appointment to get vaccinated or boosted can do so at www.vaccines.gov.