Can an LTB order be set aside if a party didn't get notice of the hearing in Ontario?

Yes — a lack of proper notice of an LTB hearing is generally one of the strongest grounds for asking the Board to review and set aside its own order under the Residential Tenancies Act, 2006. Because a party who never actually knew about a hearing had no realistic opportunity to participate or respond, this goes to a basic fairness concern the Board's own review process is specifically designed to address, separate from a general disagreement with how the case was decided on its merits.

A party seeking this kind of review generally needs to explain how and when they learned about the order after the fact, and provide whatever evidence supports the claim that notice genuinely didn't reach them, such as an outdated address on file or a documented delivery failure. The Board weighs this against the practical reality of the case, including how promptly the affected party raised the issue once they became aware of the order. Acting quickly after discovering an order was made without proper notice generally improves the chances of a successful review, since significant delay in raising the issue can itself work against the party seeking to have the order set aside.