The 49-year-old man is the first positive case after the administration started pool testing of samples, they said.
The man, a resident of the South Andaman district, has been admitted to the designated hospital, said Avijit Roy, the nodal officer for the disease in the Union Territory.
His nine family members have been sent to a quarantine facility, the officials said.
The officials said they are trying to find out how this man got infected.
The fresh case has taken the total number of people infected with the deadly virus to 12 in the Union Territory.
Ten of them tested positive after attending the Tablighi Jamaat congregation in Delhi's Nizamuddin last month, while the eleventh patient was a woman who returned from Kolkata on the same flight with them on March 24.
The ten patients were declared cured a few days back and the woman's second test report came in as negative earlier in the day, officials said.
The administration has adopted the "pool testing" method using less kits for more tests in the fight against the deadly virus. The new method has been effective for efficiently utilising the resources available to combat the coronavirus outbreak here in these remote islands, according to the officials.
The new method involves testing multiple samples in a single test. If a batch tests positive, then everyone whose samples were a part of that batch would have to be tested separately.
"Five samples per testing kit are used. So, 25 kits are required for testing 100 samples," a health department official had earlier said. CORR SOM AAR