Philip Johnston was a linen merchant and wholesale grocer who served as Mayor of Belfast during 1871.

Johnston was born at Ballinderry, County Antrim, on 24 November 1804. The family were descended from the Scottish Earl of Annadale, whose third son settled in County Down in the seventeenth century. Johnston moved to Belfast in 1827 and established a tea trading business at Rosemary Street.

He expanded into the linen industry in 1849 and was the senior partner at Johnston & Carlisle’s Brookfield Mills. Johnston subsequently joined his sons in running the Jennymount Mills and occupied the position of chairman of the company’s directorship until his death.

Philip Johnston’s term as mayor coincided with the opening of Belfast’s first town hall in Victoria Street. His was the first mayoral portrait to be displayed in the council chamber and was displayed prominently above the mayoral chair.