PurposeThis study examines the relationship between green psychological benefits and green apparel purchase behavior using stimulus–organism–response (S-O-R) theory and a serial multiple mediation model.Design/methodology/approachData were collected from 250 Lithuanians using a standardized questionnaire. Convergent and discriminant validity analyses were performed to ensure validity and reliability, and variable relationships were assessed using structural equation modeling.FindingsThe findings revealed utilitarian environmental benefits and warm glow benefits positively impacted Generation Z's (Gen Z's) attitudes toward green apparel. In contrast, the self-expressive benefits had no effect. In addition, attitude and purchase intention significantly predict green apparel purchase behavior. Attitudes and purchase intentions are crucial as serial mediators between green psychological benefits and green apparel purchase behavior.Originality/valueThese findings provide valuable insights for policymakers in Lithuania and highlight the importance of emphasizing the psychological benefits to encourage the purchase of green apparel. Moreover, policymakers and marketers should design apparel products that appeal to Gen Z, promoting green apparel adoption. By leveraging the stimulus–organism–response (S-O-R) theory, this research contributes to understanding pro-environmental behavior. It bridges the gap between attitudes, intentions and actual behavior in sustainable fashion research.