Orientation software produced today is generally designed for the navigation of cars. However, the navigation needs of pedestrians are different from those of drivers. The aim of this study is the design of a cartographic interface that supports the navigation of pedestrians in unfamiliar areas using landmarks and evaluation of this geo-mobile application by usability testing. In this study, an approach to landmark orientation based on the Voronoi diagram is proposed. Furthermore, the developed mobile application that uses this approach is explained in detail. The results of user tests are also given.