The province of Ontario first required its residents to register their vehicles and display licence plates in 1903. Along with regular series plates, the province also offers graphic plates and vanity plates with a maximum of 8 digits. Plates are currently issued by the Ontario Ministry of Transportation.

The symbol of a crown, representing the Crown of Canada, has appeared on almost all Ontario licence plates since 1937, when it was first used to commemorate the coronation of King George VI. Exceptions include the 1951 plates, and farm series plates issued in the 1980s and '90s. Toronto politician and Orange Order leader Leslie Saunders led protests against a proposal to remove the crown in 1948, a decision the government overturned.