Jamesport is a village in Riverhead, Suffolk County, New York, on the North Shore of Long Island.

James Tuthill tried to establish a commercial whaling and shipping wharf on the Peconic Bay, in what is now South Jamesport .

But the effort was unsuccessful, because the water in the Bay at low tide was too shallow to accommodate ships.

Jamesport also became a thriving fishing community, and was a center for scallop and bunker (menhaden) fisheries.

During the 1960s, the Long Island Lighting Company (LILCO) designated land adjacent to the Long Island Sound near Northville for use as the proposed Jamesport Nuclear Power Plant, in addition to its Shoreham plant, which was already under construction.