<p>Online impulse buying behavior has long attracted the attention of scholars and marketers in consumer behavior research. However, past research has primarily focused on exploring the antecedents, mechanisms, and post-purchase reactions of consumers, without addressing whether impulse buying persists after the initial purchase and what factors influence consumers’ continued impulse buying behavior. This study explores impulse buying behavior from a longitudinal perspective. It investigates whether consumers experiencing post-purchase regret following impulse buying tend to enter an impulse buying cycle, employing an input-process-output framework using 280 questionnaires. The respondents consisted of male and female consumers aged 20 to 60 from metropolitan areas in Taiwan. The study also examines whether neuroticism and temporal perspective moderate the relationship between post-purchase regret and future impulse buying behavior propensity. Path analysis (PROCESS 3.5.3 models 4 and 16) was employed to test the hypotheses. The findings reveal that post-purchase regret negatively influences future impulsive shopping tendencies, indicating that post-purchase regret inhibits future impulse buying behavior propensity. However, positive moderating effects exist. The higher the individual’s neuroticism, the more likely they are to adopt avoidance strategies, which in turn reduce the emotions of regret and reinforce future impulse buying behavior propensity. Additionally, over an extended period, individuals are likely to forget the intensity of regret, which subsequently reinforces future impulse buying behavior propensity. Unlike previous studies, we identify a reverse relationship between impulse buying and post-purchase regret.</p>