Studies have shown that attention prioritizes stimuli associated with the in‐group. However, the extent to which this so‐called in‐group favoritism is driven by relevance is not clear. Here, we investigated this issue in a group of university rowers using a novel perceptual matching task based on the team label–color associations. Across three experiments, participants showed enhanced performance for the in‐group stimulus regardless of its familiarity level. These findings confirmed the role of relevance in in‐group favoritism. In a further control study, the advantage for certain stimuli was not found in an independent sample of participants who were not identified with the teams but were familiar with the label–color associations, indicating that in‐group relevance was necessary for the in‐group favoritism. Together, these findings suggest that in‐group relevance facilitates learning across existing and new associations. The consequences of these findings for understanding in‐group effects on perceptual processing are discussed.