This article is a systematic review of 123 articles (more than twice as many articles covered by similar existing reviews) published between 1995 and 2022 in the fields of food science and sensory science, in addition to marketing and psychology. The article presents an overall picture of the findings (wherever available, we show the relevant effect size) with regard to the effects of scent on consumer behavior and reveals the remaining problems. As for future directions of research, this review focuses on the same points as two previous reviews: (1) the integration of affective and cognitive approaches and (2) the effect of unnoticed scent. However, this article further clarifies the theoretical issues with these directions. The thematic areas discussed include scent and memory, typology of scents, cultural and individual differences, negative effects of scent marketing, congruency of scent, affective approach, cognitive approach, and the effect of unnoticed scent.