It is well known that the consistency of Internet celebrity affects consumers’ purchase intention, but there are few studies on the logic behind the influence. This study investigates the impact of Internet celebrity congruence factors (celebrity congruence with the recommended products and celebrity congruence with followers) on followers’ purchasing psychological states and purchase behaviors. The research model is rooted in congruence theory and social-network theory and we conducted an empirical study on Tiktok and IG followers of celebrities. Then, we used partial least squares structural equation modeling (PLS–SEM) to analyze 297 valid questionnaires. The results show the congruence of Internet celebrity with both followers and products promotes follower product adoption; the congruence does so by enhancing followers’ perception that the recommendations are credible, in turn increasing the followers’ confidence in, desire for, and motivation to buy the product. This study explains that the congruence of Internet celebrities with followers and products must be strongly present in the recommendation, which leads to a high credibility recommendation. A high credibility recommendation greatly influences consumers’ pre-purchase psychological states and thus enhance their purchase intention. This study demonstrates to practitioners that when consumers’ purchase intention is lower than expected, it is necessary to consider the credibility of the recommendation.