The city says the person with the variant is fully vaccinated and is not experiencing any significant symptoms. The person recently traveled internationally and returned to Long Beach on Nov. 29. The city health department learned of the case on Monday.
No additional details were released about the individual's identity, travel or contacts.
The omicron variant has been detected in at least 50 countries and 19 U.S. states.
Multiple California cases have been reported. Los Angeles County had reported three cases prior to Long Beach announcing its first case on Tuesday.
Omicron is believed to be a highly transmissible variant of COVID-19, but researchers are still studying to determine if it is more dangerous than other variants, such as delta.
Long Beach authorities are reminding residents that the best protection against COVID-19 is vaccination, in addition to measures such as wearing masks and getting tested.
Information is available here about vaccination for Long Beach residents. The state vaccination website, MyTurn, is here.