With the increasing influence of social media, social media influencers (SMIs) have become key players in shaping consumer behavior, particularly in driving online impulsive buying behavior (OIBB). This study investigates how SMIs' interpersonal interaction and social attraction impact followers' parasocial interaction (PSI) and examines PSI's mediating role in OIBB. Using a modified Stimulus-Organism- Response (S-O-R) model, data were collected from 589 participants in Turkey through an online survey. The findings indicate that similarity, likeability, and social attraction significantly influence PSI, which, in turn, encourages OIBB. However, expertise does not play a significant role in fostering PSI. Moreover, PSI mediates the relationships between likeability and OIBB, as well as social attraction and OIBB, but does not mediate the effects of similarity or expertise. These insights suggest that SMIs' ability to form personal and social bonds with followers is more influential in triggering impulsive purchases than their perceived expertise. The study provides strategic implications for marketers seeking to enhance engagement and drive sales through influencer- driven digital marketing campaigns.