The Ministry of Transportation (MTO) is the provincial ministry of the Government of Ontario that is responsible for transport infrastructure and related law in Ontario, Canada. The ministry traces its roots back over a century to the 1890s, when the province began training Provincial Road Building Instructors. In 1916, the Department of Public Highways of Ontario (DPHO) was formed and tasked with establishing a network of provincial highways. The first was designated in 1918, and by the summer of 1925, sixteen highways were numbered. In the mid-1920s, a new Department of Northern Development (DND) was created to manage infrastructure improvements in northern Ontario; it merged with the Department of Highways of Ontario (DHO) on April 1, 1937. In 1971, the Department of Highways took on responsibility for Communications and in 1972 was reorganized as the Ministry of Transportation and Communications (MTC), which then became the Ministry of Transportation in 1987.

The Government of Ontario is the body responsible for the administration of the Canadian province of Ontario. The term Government of Ontario refers specifically to the executive—political ministers of the Crown, appointed on the advice of the premier, and the non-partisan Ontario Public Service, who staff ministries and agencies to deliver government policies, programs, and services—which corporately brands itself as the Government of Ontario, or more formally, His Majesty's Government of Ontario.