Syosset /saɪˈɒsɪt/ is a hamlet and census-designated place in the Town of Oyster Bay, in Nassau County, on the North Shore of Long Island, in New York, United States.

According to the U.S. Census Bureau, Syosset has a total area of 5.0 square miles (13 km2), all land.

It borders Oyster Bay and Laurel Hollow to the north, Woodbury to the east, Plainview and Hicksville to the south, and Jericho and Muttontown to the west.

Syosset is accessible to New York City by the LIRR and the Long Island Expressway by car.

[6] The Syosset Fire Department currently operates out of three fire stations, located throughout the area, which encompasses Syosset, Woodbury, and parts of Muttontown, Oyster Bay Cove, Laurel Hollow, Cold Spring Harbor, East Norwich, Jericho, Hicksville, and Plainview.

[17] They operate a fire apparatus fleet of five engines, two trucks, one rescue, three ambulances, and several special, support, and reserve units.