Restricted by the small screen size, it is challenging for users to obtain all the wayfinding content they need when utilizing mobile devices. This study investigated the effects of map size and interactive interface on users’ wayfinding performance and preference when using mobile devices. Two types of interactive interfaces (i.e., panning and peephole interfaces) and three different map sizes (i.e., small, medium, and large) were examined. The experiment was a 2 × 3 between-subjects design. Sixty participants were invited to complete five wayfinding tasks (i.e., Euclidean distance judgment, route distance judgment, landmark recognition, map section rotation, and route recognition), a system usability scale (SUS) questionnaire, and the subjective preference questionnaire. The results showed that: (1) The participants’ wayfinding performance was affected by the map size and interactive interface; (2) the peephole interface was superior for the Euclidean distance judgment and the route recognition tasks; (3) it does not always take a significantly longer time to complete the task with the larger map when performing the map section rotation task with the panning interface; and (4) the usability scores of the peephole interface were considered above average, and it had a positive impact on the participants’ preferences.