Purpose The purpose of this paper is to investigate fashion blogs’ influence on Spanish Millennials’ buying behaviour. Design/methodology/approach This research is quantitative in nature, utilising a mono method consisting of structured self-administered questionnaires. Data were exported to IBM SPSS Statistics, where different types of analyses were combined – such as frequencies, means, hypothesis testing analyses, principal components analysis or K-means cluster. Findings Findings show that the most important motivations to follow a fashion blog are entertainment and information seeking. Besides, consumers’ attitudes seem to be influenced by how consumers assess credibility, which is determined by trustworthiness, para-social interaction (PSI), expertise and message credibility. Finally, after showing covert and overt marketing posts, both trustworthiness and PSI were lower than before, identifying PSI as a possible moderator in these cases. Research limitations/implications The main limitation of this study is the sample size, which does not make it possible to generalise conclusions. Practical implications From this research, it can be said that, due to the importance of establishing a strong relationship with the public, bloggers should try to connect with readers on an emotional level, and brands need to select bloggers very carefully. Originality/value This paper reveals Millennials’ attitudes whilst they are visiting a fashion blog and the influence that these attitudes can exercise on their purchase intention.