The main objective of this study is to evaluate the mediating role of credibility in purchase intention on social media, considering predictor variables such as emotional and functional value in social media in the structural model. Using a quantitative research approach with a non-experimental, cross-sectional, and explanatory design, covariance-based structural equation modelling (CBSEM) was used for data processing and analysis. The sample consisted of 300 male and female university students from different careers. The most important result is the confirmation that perceived credibility is the decisive mechanism that transforms the value of social media content into purchase intention. When messages are emotional, a purchase only occurs if they first generate trust. Trust almost doubles their direct persuasive power when functional, consolidating credibility as an indispensable bridge between engagement and purchase action. It is concluded that perceived credibility acts as an essential bridge, converting social media content’s functional and emotional value into purchase intent among university students. When the message provides tangible benefits, trust amplifies its persuasive impact; when it appeals to emotions, trust is essential for emotional attraction to translate into action.