Knee osteoarthritis (OA) is a serious disease and has no cure to date. Knee OA is a leading cause of functional limitation, e.g., difficulty walking. Walking speed is one method of quantifying difficulty with walking, and should be assessed in clinical practice for adults with knee OA because it has prognostic value and is modifiable. Specifically, slow walking speed is associated with increased risk of adverse health outcomes, including all-cause mortality in adults with knee OA and can be modified by engaging in physical activity or exercise. However, at present, there is little consensus on the distance and instructions used to conduct the walk test. Distance is often selected based on space availability, and instruction varies from asking the participants to walk at a comfortable pace vs. as fast as possible. Therefore, the purpose of this narrative review is to summarize the measurement properties, strengths, and limitations of a fixed-distance walk test less than 40 meters in adults with knee OA. Good measurement properties in terms of reliability and validity were observed across the different testing protocols for fixed-distance walk test, i.e., any distance ≤ 40 meters and fast- or self-paced. Therefore, clinicians and researchers can select a testing protocol that can safely and consistently be performed over time as well as provide a practice trial to acclimatize the patients to the fixed-distance walk test.