John Alexander Mathieson
12th Premier of Prince Edward Island
In office December 2, 1911 – June 21, 1917
Monarch	George V
Lieutenant Governor	Benjamin Rogers Augustine Colin Macdonald
Preceded by	H. James Palmer
Succeeded by	Aubin-Edmond Arsenault
Leader of the Conservative Party of Prince Edward Island
In office 1903 – June 21, 1917
Preceded by	Daniel Gordon
Succeeded by	Aubin-Edmund Arsenault
MLA (Assemblyman) for 4th Kings
In office December 12, 1900 – December 7, 1904
Preceded by	Albert Prowse
Succeeded by	Albert Prowse
MLA (Councillor) for 5th Kings
In office December 7, 1904 – June 21, 1917
Preceded by	Daniel Gordon
Succeeded by	James David Stewart
Administrator of Prince Edward Island
In office July 16, 1919 – September 2, 1919
Preceded by	Augustine Colin Macdonald
Succeeded by	Murdock MacKinnon
In office December 9, 1933 – December 28, 1933
Preceded by	Charles Dalton
Succeeded by	George Des Brisay de Blois
Personal details
Born	(1863-05-19)May 19, 1863 Harrington, Prince Edward Island Colony
Died	January 7, 1947(1947-01-07) (aged 83) Charlottetown, Prince Edward Island, Canada
Nationality	Canadian
Political party	Conservative
Spouse	Mary Alice I-aird ​ (m. 1896)​
Children	5
Residence	Georgetown, Prince Edward Island
Alma mater	Prince of Wales College
Occupation	Teacher, principal, lawyer
Profession	Politician

John Alexander Mathieson (May 19, 1863 – January 7, 1947) was a politician and jurist of Prince Edward Island, Canada, and the 12th premier.

Mathieson was born in Harrington and graduated from Prince of Wales College. He was a schoolmaster and lawyer before entering politics with his election to the province's legislature as a Conservative in 1900. He represented the district of 4th Kings in his first term in the legislature, then shifted to 5th Kings in 1904.

Mathieson sat on the opposition benches, becoming Leader of the Opposition and of the Conservative Party in 1903. In December 1911, the Liberal government resigned when Premier H. James Palmer was defeated in a by-election which also caused the governing Liberals to lose their majority in the legislature. The Lieutenant-Governor of Prince Edward Island asked Mathieson as leader of the opposition to form a government, which he did, going on to win a mandate in the 1912 general election.

Mathieson's government pressed the federal government to fulfill the terms on which Prince Edward Island joined Canadian Confederation in 1873. He succeeded in persuading Ottawa to provide an improved annual subsidy to the province and, in 1915, Ottawa announced the creation of a year-round ferry service to connect the island to the mainland. The ferries began operating between PEI and New Brunswick in 1917.

The province was also at risk of losing representation in the House of Commons of Canada due to population shifts. PEI had six MPs when it joined confederation in 1873, this was reduced to four and was to be cut further as a result of the 1911 census. Mathieson persuaded the federal government to agree to an amendment to the British North America Act guaranteeing the province a minimum of four MPs in perpetuity.

In 1917, Premier Mathieson left politics to accept an appointment as Chief Justice and served in that position until he retired in 1943.

• Government of Prince Edward Island biography