In the past few years, internet celebrities have become a new and important way to get people to buy energy-saving products. Their psychological mechanisms for promoting fans’ intention to purchase have become the focus of academic attention, but a unified conclusion has yet to be reached. This study uses online communities as a scenario, with the characteristics of influencers’ expertise, social attraction, and task attraction as antecedent variables and social cognitive theory and parasocial interaction theory as the theoretical basis to explore their influence on fans’ intention to purchase household energy-saving products. The study investigates the mediating role of parasocial relationships and the moderating role of fans’ green self-efficacy in influencing internet celebrities’ expertise and attraction of fans’ parasocial relationships. The results showed that the parasocial relationships formed between fans and influencers mediated the relationship between the expertise and attraction of influencers and fans’ intention to purchase energy-saving products and that “green self-efficacy” positively moderated the parasocial relationships formed between fans and internet celebrities in terms of their expertise and task attraction. The moderating effect of “green self-efficacy” on the parasocial relationships between fans and internet celebrities was insignificant.