The internet enables consumers not only to buy products anywhere and at any time but also to compare prices and make informed consumption decisions. However, the increased convenience resulting from advancements in technology has simplified consumers' decision-making process, thereby leading to impulse buying behaviour. In the present study, the differences among consumers' impulse buying behaviour, purchase satisfaction, and complaint behaviour were compared based on the types of product purchase decisions (online v. offline). A total of 382 customers who had previously bought sportswear and voluntarily participated in the present study were divided into two groups, based on their preferred type of purchase. The respondents completed a questionnaire survey regarding their impulse buying behaviour, purchase satisfaction, and complaint behaviour. SPSS/AMOS 23.0 version was used to confirm the reliability and credibility of the collected data, and a multivariate analysis of variance was used to compare the participants' questionnaire responses regarding their consumption behaviour, based on their preferred type of purchase. The results showed that although consumers who preferred online purchasing were increasingly likely to exhibit impulse buying behaviour, they did not complain about their purchase dissatisfaction. In comparison, although consumers who preferred offline purchasing were more satisfied with the product they bought, they indulged in private complaint behaviour regarding their purchase dissatisfaction. The study results show that consumers exhibited different behaviours, depending on their preferred type of purchase. The present study results serve as an important reference for understanding evolving consumption trends through a multi-faceted approach.