Seaforth is a suburb of Northern Sydney, in the state of New South Wales, Australia.

Seaforth overlooks Middle Harbour and is linked south to Mosman by the Spit Bridge.

To the west, Seaforth overlooks Sugarloaf Bay across to the suburbs of Northbridge, Castlecrag and Castle Cove.

Seaforth celebrated its centenary on Sunday 12 November 2006 with a historical display in the town centre.

The Seaforth shopping district is located off Sydney Road and offers a wide variety of services, including niche market products.