Kitchener-Waterloo (a.k.a K-W) is an unofficial but ubiquitous name for the area in Ontario, Canada consisting of the twin cities of Kitchener and Waterloo, approximately 100 kilometres west of Toronto. The two cities grew into each other decades ago and their shared boundary cuts through streets, backyards and houses. While the term is frequently used by local residents, those who would use it should be aware that Kitchener and Waterloo are separate cities and that writing or saying "Kitchener-Waterloo" in a way that implies a single municipal entity may incur the displeasure of some residents.

The term is often used to describe joint ventures between the two cities and other initiatives that draw upon resources in both Kitchener and Waterloo, such as Kitchener-Waterloo Oktoberfest, K-W Health Centre, Kitchener-Waterloo Symphony, Kitchener-Waterloo Art Gallery, Kitchener-Waterloo Santa Claus Parade, and Kitchener-Waterloo Humane Society.