Supervision stands as one of the most critical yet frequently misunderstood elements of occupational health and safety due diligence in Canadian workplaces. While employers often focus on developing comprehensive safety policies, providing training programs, and investing in personal protective equipment, the ongoing supervision of work activities represents the practical bridge between written safety systems and actual safe work performance. Without effective supervision, even the most robust safety policies become theoretical documents that fail to protect workers or establish a credible due diligence defence when regulatory authorities investigate incidents or when charges are laid under occupational health and safety legislation. The legal foundation for supervision as a due diligence element flows directly from the general duty provisions found in occupational health and safety statutes across all Canadian jurisdictions. Federal workplaces operating under the Canada Labour Code face explicit requirements for employers to ensure that the health and safety at work of every person employed by the employer is protected, and this protection cannot be achieved through policy alone but requires active oversight of how work is actually performed. Provincial legislation across British Columbia, Alberta, Saskatchewan, Ontario, and Quebec establishes parallel obligations, each requiring employers to take reasonable precautions to protect worker health and safety. As of the date of authorship, these general duty provisions have been interpreted consistently to include the obligation to supervise work activities in a manner that ensures compliance with safe work practices and identifies hazards before they result in injuries or fatalities.