The positive result was detected during testing in a government-managed quarantine facility on Monday evening.
The case is the fourth reported for Nauru.
President Lionel Aingimea announced this morning that the person displayed mild symptoms of fever but otherwise stable and well.
This is the only active case today.
All previous cases have recovered and are no longer active.
The person travelled on the Sunday 24 April flight from Brisbane to Nauru has been in quarantine since then. This is the only case detected from Sunday’s flight.