Six preregistered studies show that the degree of similarity of two objects biases people’s spatial memory of these objects. When objects are high in similarity, people remember having seen them closer together in space than when they are low in similarity. All six studies provide correlational evidence, showing that the more similar participants rated two stimuli, the smaller they remembered the distance between them. This was true for both conceptual and perceptual similarity (Study 3). Furthermore, Studies 2, 4A, and 4B provide evidence of causality by manipulating similarity experimentally. Replicating the correlational findings, highly similar stimuli were remembered as closer together than stimuli low in similarity. This pattern was found across different stimulus categories and similarity dimensions. Overall, these findings show that the similarity of stimuli influences perceivers’ reconstruction of their spatial locations.