The effect of semantic knowledge in an everyday wayfinding task was investigated in real and virtual grocery stores. Participants had to search for food items of varying degrees of congruency with background knowledge with respect to their placement. Food categories and the congruency of categories with the placement of pertinent items was assessed pre-experimentally using a card-sorting task. Exp. 1 was conducted in a real supermarket (tracing participants by means of RFID techniques) and replicated in a virtual environment (Exp. 2). Exp. 3 used a VR variation where all the pictures on the shelves of the VR supermarket were replaced with printed labels. Semantic knowledge yielded stable and fairly high effect sizes across experimental conditions, revealing that semantic congruency with placement made the search much more efficient. The results show that even abstract background knowledge (semantic categories) may be involved in human navigation.