He was elected to the Legislative Assembly of Ontario in 1913 as a Conservative in the riding of York East.
In 1918 he was appointed as Minister of Agriculture.
In 1920 he ran for the leadership of the provincial Conservatives at that party's first ever leadership convention but lost to Howard Ferguson who led the party to victory in the subsequent general election.
From 1923 to 1930, Henry served as Minister of Highways in the Ferguson government, expanding on the highway system that was initiated by the previous government of Ernest C. Drury.

When Ferguson stepped down in 1930, barely a year into the Great Depression, Henry succeeded him as Conservative party leader and Premier of Ontario.
Henry continued the programme of building roads, extending Ontario's highway system from 670 km to 3888 km.

Construction of Canada's first four-lane controlled access superhighway, the Toronto to Niagara Falls Queen Elizabeth Way, is the most lasting achievement of the highway program.
Henry was opposed to government intervention to deal with the economy.
 Aside from building roads, his government did little to alleviate public suffering during the Depression, such as unemployment in the cities, or the collapse of prices for farm products in the country.
Henry's government, like the federal government of R.B. Bennett, established work camps for jobless men.
They were established not so much to provide social welfare, but rather as social control, i.e., to evacuate this potentially radical element from the cities.
 The work camps  also provided a source of labour for the construction of Henry's highway system.

In the 1934 election, Henry sought a new mandate from the voters in his first election as Premier.
Some felt the government had little to offer beyond more road construction, and the Tories were soundly defeated by the Ontario Liberal Party led by Mitchell Hepburn.
He became the Leader of the Opposition from 1934, until he retired as the  Conservative leader in 1938.
He was elected to the Legislative Assembly of Ontario in 1913 as a Conservative in the riding of York East. In 1918 he was appointed as Minister of Agriculture. In 1920 he ran for the leadership of the provincial Conservatives at that party's first ever leadership convention but lost to Howard Ferguson who led the party to victory in the subsequent general election. From 1923 to 1930, Henry served as Minister of Highways in the Ferguson government, expanding on the highway system that was initiated by the previous government of Ernest C. Drury.
When Ferguson stepped down in 1930, barely a year into the Great Depression, Henry succeeded him as Conservative party leader and Premier of Ontario. Henry continued the programme of building roads, extending Ontario's highway system from 670 km to 3888 km.
Construction of Canada's first four-lane controlled access superhighway, the Toronto to Niagara Falls Queen Elizabeth Way, is the most lasting achievement of the highway program. Henry was opposed to government intervention to deal with the economy.  Aside from building roads, his government did little to alleviate public suffering during the Depression, such as unemployment in the cities, or the collapse of prices for farm products in the country. Henry's government, like the federal government of R.B. Bennett, established work camps for jobless men. They were established not so much to provide social welfare, but rather as social control, i.e., to evacuate this potentially radical element from the cities.  The work camps  also provided a source of labour for the construction of Henry's highway system.
In the 1934 election, Henry sought a new mandate from the voters in his first election as Premier. Some felt the government had little to offer beyond more road construction, and the Tories were soundly defeated by the Ontario Liberal Party led by Mitchell Hepburn. He became the Leader of the Opposition from 1934, until he retired as the  Conservative leader in 1938.
George Stewart Henry