This study examined the relationship between fashion uniqueness and wearer creativity, and investigated the cognitive mechanisms and boundary conditions underlying this relationship. Fashion is closer to the individual wearing it than any other possession, and wearers express themselves through fashion; therefore, for others, a wearer's fashion becomes an important external cue for perceiving and judging that person. Wearers also constantly consider that others may perceive them through their fashion. This study confirmed that "fashion uniqueness" positively influences "wearer creativity," and that in this process, "self-perceived conspicuousness" (the degree to which one perceives that others are paying attention to oneself) operates as an underlying psychological mechanism; "self-perceived conspicuousness" does not directly affect "wearer creativity" per se, but is rather moderated by the direction and degree of the "wearer's extraversion-introversion." This is driven by expectancy theory (Vroom, 1964), whereby the psychology of wanting to fulfill others' expectations of perceiving oneself as a unique being—given that one is wearing unique fashion—serves as the driving force. This study consisted of three experiments. In Study 1, by analyzing the fashion actually worn by participants, it was confirmed that people with higher fashion uniqueness exhibited higher creativity. In Study 2, it was verified that the personality trait of extraversion-introversion had a moderating effect on the relationship between fashion uniqueness and wearer creativity. When fashion uniqueness was high, higher extraversion was associated with higher wearer creativity. However, when fashion uniqueness was low, no moderating effect of extraversion-introversion was confirmed. In Study 3, it was verified that extraversion-introversion had a moderated mediation effect through self-perceived conspicuousness in the relationship between fashion uniqueness and wearer creativity. This is because extraversion-introversion produces differential reactions to others' attention toward oneself, and therefore extraversion-introversion moderates the effect of self-perceived conspicuousness on wearer creativity.