Cannabis in Idaho is fully illegal for any use, whether recreational or medical. The laws on cannabis prohibition in Idaho are among the most severe in the United States, with possession of even small amounts of it a misdemeanor crime, and no legality of medical marijuana. As of 2018, support for the legalization of medical cannabis is broadly popular in the state, while legalization of the drug recreationally remains a wedge issue. Both the state's legislature as a whole and its governor, Brad Little, remain staunchly opposed to its legalization for medicinal or recreational purposes.

In February 2021, cannabidiol with up to 0.1% THC content was descheduled in the form of the prescription drug Epidiolex. Two months later, production and transport of hemp with a THC content of up to 0.3% was legalized.