Can a protection order obtained in one Ontario city be enforced if the other party moves to a different city?

Yes — a restraining order or similar protection order made by an Ontario family court is valid and enforceable throughout the province, not just in the city or courthouse where it was granted. It doesn't need to be re-registered or re-issued in a different Ontario city to remain effective; police anywhere in Ontario can act on a valid order and its terms, and a breach can be reported to police wherever it occurs, regardless of where the original order was made.

What does matter practically is making sure the order and any supporting information are accessible and up to date — keeping a copy of the order on hand, informing police in the new location if there's an ongoing concern, and updating contact information with the court if relevant to the order's conditions. If the other party moves within Ontario, the original order continues to apply to them wherever they are in the province; more complex situations arise if someone moves to a different province or country, where a separate process is generally needed to have the order recognized and enforced there.