The aim of this study is to assess whether social media addiction contributes to the intention to buy; it is based on the model of Hajli (2014) that assesses the relationships between the constructs of social media use, trust, perceived usefulness, and intention to buy in social media sites. To this end, a confirmatory factor analysis was carried out to evaluate whether the Hajli model applied to this sample, as well as multigroup CFA to measure invariance across gender and across following influencers or not. Finally, the path analysis evaluates the intersection of social media addiction with the Hajli model (2014). The results confirmed the Hajli model as well as the inclusion in the model of social media addiction as a variable that contributes to purchase intention on social media. Configural, metric, and scalar invariance were found across genders and across the following influencers or not. Also, the values found for internal consistency and composite reliability, convergent reliability, and discriminant reliability were within the reference values.