Canadian employment law does not specifically preclude employees from moonlighting on the side by working for themselves or for another business after hours, unless this contravenes their employer's code of conduct or employment contract, or involves an inherent conflict of interest with the employee's day job.

Can an employer prevent you from working a second job Canada?

Employers do have the ability to restrict employees from working a second job but won't prohibit the activity as long as it doesn't affect your work performance, or it's not for a competitor. Why Do Employers Care about Multiple Job Holding (Moonlighting)?

Can you get in trouble for moonlighting?

Even if it doesn't violate a written policy, moonlighting can still be illegal (and can get you sued) if it violates a “duty of loyalty” to an employer – for instance, if you use an employer's ideas or customers to start your own business. ... An employer can absolutely ban moonlighting in many cases.