With the rapid development and adoption of artificial intelligence (AI), the emergence of AI-generated influencers has surged in the public sphere. The current paper aims to investigate the endorsement effectiveness of AI influencers by exploring the psychological mechanism underlying the characteristics of AI influencers and consumers’ purchase intention. About 500 samples were collected from China through an online survey to (1) measure the multidimensional scale of social media presence, fantasy, attitude towards the endorser, and purchase intention; and (2) test the relationships among these variables. The results show that social media presence exerted positive and significant effects on purchase intention, fantasy, and attitude towards the endorser. Additionally, fantasy positively correlated with purchase intention and attitude towards the endorser. Furthermore, attitude towards the endorser positively influenced purchase intention. This paper explains the underlying reasons for consumers fantasizing about AI influencers for multiple gratifications on social media. It is based on the Uses and Gratifications Theory (UGT) as the internal psychological mechanism for determining the effectiveness of AI influencers’ endorsement, rather than solely relying on interpersonal social interaction as explained by para-social interaction. This approach offers a new perspective on AI influencer endorsement and its future study. This paper presents a new theoretical basis and key findings for AI influencer endorsements in addition to providing significant management guidance on AI influencer incubation and AI influencer endorsement selection for marketers. Moreover, the conclusions from this study serve as valuable references for policymakers in shaping regulations related to AI-driven advertisements, promotions, and campaigns.