The dynamic impact of electronic word-of-mouth (eWOM) valence on consumer attitudes and perceptions emphasizes the necessity of understanding how online reviews influence consumer behavior in the digital age. This study thus addresses this challenge by integrating the perspectives of the Stimulus-Organism-Response (SOR) model with trust transfer theory and the Theory of Planned Behavior (TPB) as the theoretical foundation for the proposed conceptual research framework. Employing structural equation modeling (SEM), this study analyzed experimental survey data collected from 601 Indonesian Instagram users in August 2023. The findings reveal that eWOM valence positively affects consumer brand attitudes and perceived brand quality, subsequently driving online engagement and purchase intentions. The study challenges established relationships by demonstrating how brand attitude and perceived brand quality mediate the influence of eWOM valence. Additionally, this study highlights the critical moderating roles of eWOM credibility and influencer familiarity in strengthening the impact of eWOM valence. This research scrutinizes a context not widely explored in the current literature of eWOM studies by integrating these moderators and focusing on the dynamic interactions within social media platforms, providing new insights for digital marketers and social media influencers aiming to enhance consumer engagement and purchase intentions in the digital domain.