This study used intervention mapping to develop a print intervention that promotes dog walking for physical activity among dog owners. Twenty-six adult dog owners were recruited to participate in an interview about dog walking. Eight major themes emerged from the individual interviews: obligation to the dog, motivation from the dog, self-efficacy, dog’s health, owner’s health, socialization, “an active dog is a better-behaved dog”, and having a routine. Determinants of dog walking identified in the interviews and in a literature review were used to create a matrix of change objectives. Theory-based methods and practical applications were chosen for the brochure, which was then developed and piloted among five participants. The resulting brochure is based on theory and evidence and can be used to promote regular dog walking. Future research should focus on implementation and evaluation of this resource as well as the development of other interventions targeting dog owners.