Nowadays, social media influencers are one of the most important assets of many businesses that originate purchase decisions. The relevance of this paper is determined by the fact that it tries to fill in the research gap of literature determining the factors that might influence the purchase decisions of millennial consumers based on the theories of the constructs. The purpose is to determine the impact of brand value on the credibility of influencers over the purchase decision. Therefore, 412 millennial consumers from the city of Arequipa, Peru, were surveyed through an online form provided by Google. Then, the validation and descriptive statistics were made on the program SPSS. Additionally, the inferential statistics using the software Smart PLS. The results show a positive, significant, and direct relationship between the credibility of influencers and customers’ purchase decisions. Moreover, this relationship increases through the brand value when incorporated into the model as a mediator variable, facilitating the decision of consumers. In conclusion, it was estimated that consumers feel even more confident when social media influencers transmit the message showing specific brand attributes.