The Occupational Health and Safety Act, the Employment Standards Act, 2000 and the Workplace Safety and Insurance Act specify exact posting requirements for employers in Ontario.

Posters

Health & Safety at Work: Prevention Starts Here: Printed colour posters are available in English and French from Service Ontario free of charge or can be downloaded in English, French and 16 other languages.
What You Should Know About The Ontario Employment Standards Act, 2000: It is available online for free, and ServiceOntario Publications provides printed copies of the poster, charging only for shipping and handling.
In Case of Injury—1234: Form 82 It is provided free of charge by the Workplace Safety and Insurance Board (WSIB). Call the WSIB at 416-344-1016 or 1-800-663-6639.

Documents

Occupational Health and Safety Act: Employers are required to post a copy of the Occupational Health and Safety Act (OHSA) in their workplaces. It is available online for free. It is also available from ServiceOntario Publications.
Health and Safety Policy: The OHSA also requires employers to prepare and review, at least once a year, a written occupational health and safety policy, and to develop and maintain a program to implement that policy. The policy must be posted in the workplace.
Workplace Violence and Workplace Harassment: The OHSA requires employers to prepare and review, at least once a year, workplace violence and workplace harassment policies, and to develop and maintain programs to implement those policies. These policies must be in writing and posted in the workplace except for workplaces with five or fewer regularly employed workers, unless ordered by an inspector.
Joint Health and Safety Committees: In workplaces where the employer is required to establish a joint health and safety committee, the employer must also post the names and work locations of the committee members in a conspicuous place.


https://www.labour.gov.on.ca/english/hs/pubs/hsawtoday/issue2.php#posting