Smoking bans, or smoke-free laws, are public policies, including criminal laws and occupational safety and health regulations, that prohibit tobacco smoking in certain spaces. The spaces most commonly affected by smoking bans are indoor workplaces and buildings open to the public such as restaurants, bars, office buildings, schools, retail stores, hospitals, libraries, transport facilities, and government buildings, in addition to public transport vehicles such as aircraft, buses, watercraft, and trains. However, laws may also prohibit smoking in outdoor areas such as parks, beaches, pedestrian plazas, college and hospital campuses, and within a certain distance from the entrance to a building, and in some cases, private vehicles and multi-unit residences.

The most common rationale cited for restrictions on smoking is the negative health effects associated with secondhand smoke (SHS), or the inhalation of tobacco smoke by persons who are not smoking. These include diseases such as heart disease, cancer, and chronic obstructive pulmonary disease. The number of smoking bans around the world increased substantially in the late 20th century and early 21st century due to increased knowledge about these health risks. Many early smoking restrictions merely required the designation of non-smoking areas in buildings, but policies of this type became less common following evidence that they did not eliminate the health concerns associated with SHS.

Opinions on smoking bans vary. Many individuals and organizations such as the World Health Organization (WHO) support smoking bans on the basis that they improve health outcomes by reducing exposure to SHS and possibly decreasing the number of people who smoke, while others oppose smoking bans and assert that they violate individual and property rights and cause economic hardship, among other issues.