Donald Farquharson (July 27, 1834 – June 26, 1903) was a Canadian politician who served as the eighth premier of Prince Edward Island.

A native of Mermaid, Farquharson had been a teacher and then a businessman involved in wholesale and shipping.

Farquharson sat in opposition until the Liberals won the 1891 election.

He became Premier in August 1898 but, in 1901, he was persuaded to run in a by-election to the federal House of Commons since PEI Liberals hoped that as a former Premier, he would be elevated to the Canadian cabinet guaranteeing the island's representation in government.

During Farquharson's premiership the provincial legislature passed the Prohibition Act (or Scott Act) which implemented a complete ban on alcohol sales and production in the province starting in 1901.