Can an Ontario employer prevent a departing employee from recruiting former coworkers to a new job?

Yes, generally, through a properly drafted non-solicitation clause in the employment contract. This type of clause specifically restricts a departing employee from soliciting or recruiting former colleagues to leave and join them at a new employer for a defined period after their own departure, and it's a common and legitimate way for a business to protect its workforce from being poached in a coordinated way by someone who just left with detailed knowledge of the team.

Like other restrictive covenants, a non-solicitation clause aimed at former coworkers still has to be reasonable to be enforced — reasonable in how long it lasts, and reasonable in scope, such as which employees or roles it actually covers, rather than an indefinite or overly broad restriction on contacting anyone who ever worked at the company. Courts will look at whether the clause genuinely protects a legitimate business interest, like workforce stability, rather than simply punishing an employee for leaving.

This kind of clause is not affected by the ESA's ban on non-compete agreements, since it doesn't restrict where the departing employee can work, only who they can actively try to recruit. Getting the clause's wording right at the drafting stage makes it far more likely to hold up if it's ever tested.