Cannabis in Ontario is legal for both medical and recreational purposes. Cannabis in Canada has been legal for medicinal purposes since 2001 under conditions outlined in the Access to Cannabis for Medical Purposes Regulations, issued by Health Canada, while seed, grain, and fibre production are permitted under licence. The federal Cannabis Act, legalizing cannabis for recreational use, came into effect on 17 October 2018.

The Cannabis Act tasks each province and territory to set its own laws for various aspects regarding recreational use cannabis, such as the legal age, whether householders can grow cannabis and the method of retail sales. The latter aspect varies as to ownership of retail outlets (by the provincial government or private enterprise) but all provinces and territories include an option for on-line sales.

In 2019, the Ontario government initially issued 25 retail licenses for brick-and-mortar stores to sell recreational cannabis; the selection was based on strict criteria and a lottery system. An additional 50 licenses were subsequently issued. By April 2020, the government planned to eliminate the lottery system and to begin issuing roughly 20 new permits per month to increase availability as part of the plan to combat sales by black market dealers. Retail on-line sales of recreational cannabis remained in the hands of the Ontario Cannabis Store, operated by the provincial government.