Ralph Torres sent the request to Donald Trump overnight as the storm passed over the island of Rota.
Mr Torres said the heightened and erratic state of the storm threatened destruction and the impact could become catastrophic.
The statement said the worst conditions from Typhoon Mangkhut had passed but windshield assessments indicated significant damage on Rota and some damage on the islands of Saipan and Tinian.
The governor said the storm was of such severity and magnitude that an effective response was beyond the capabilities of the CNMI government and federal assistance was needed to save lives and protect property, health and safety.
Rota bore the brunt of Typhoon Mangkhut with the storm dumping up to 255mm of rain and winds of over 223 kilometres an hour hitting the CNMI's southern most island.
Over 600 people reportedly sought shelter in evacuation centres during the storm.
Government offices remain closed today.
Photo source The Weather Channel. Caption: Typhoon Mangkhut lashes Northern Marianas .