Cuomo told a daily briefing that the boy died in New York City on Thursday.
He said health officials were investigating 73 similar cases reported across New York where children have exhibited symptoms similar to Kawasaki disease or toxic shock-like syndrome linked to COVID-19, the respiratory illness caused by the coronavirus.
"While rare, we are seeing some cases where children affected with the COVID virus can become ill with symptoms similar to the Kawasaki disease or toxic shock-like syndrome that literally causes inflammation in their blood vessels," he said.
Cases of rare, life-threatening inflammatory illnesses in children associated with exposure to COVID-19 were first reported in Britain, Italy and Spain, but doctors in the United States are starting to report clusters of kids with the disorder, which can attack multiple organs, impair heart function and weaken heart arteries.
"This would be really painful news and would open up an entirely different chapter," Cuomo said. "I can't tell you how many people I spoke to who took peace and solace in the fact that children were not getting infected."
This emerging syndrome, which may occur days to weeks after a COVID-19 illness, reflects the surprising ways that this entirely new coronavirus infects and sickens its human hosts.
Scientists are still trying to determine whether the syndrome is linked with the new coronavirus as not all children have tested positive for the virus.
The syndrome shares symptoms with toxic shock and Kawasaki disease, which is associated with fever, skin rashes, swelling of glands, and in severe cases, inflammation of arteries of the heart.