Portstewart (Irish: Port Stíobhaird) is a small seaside town in County Londonderry, Northern Ireland.

Its harbour and scenic coastal paths form an Atlantic promenade leading to a two-mile beach (Portstewart Strand), popular with holidaymakers in summer and surfers year-round.

According to the University of Ulster Quarterly House Price Index report produced in partnership with Bank of Ireland and the Northern Ireland Housing Executive in Q4 2010, the North Coast region (Coleraine/Limavady area) had higher property prices than those of affluent south Belfast.

[8] Portstewart developed to a modest size seaside resort in the mid 19th century under the influence of a local landlord, John Cromie.

Its development and character was influenced greatly by the Sabbatarian sensitivities of the Cromies and the consequent resistance to a railway connection in the mid 19th century.

On Census day (27 March 2011) there were 8,003 people living in Portstewart (3,338 households), accounting for 0.44% of the NI total.