Climate change conspiracy beliefs may undermine our efforts to tackle climate change. Previous studies have conceptualized the influence of climate change conspiracy beliefs as an individual's behavioral decision-making process, overlooking the possible consequences of such beliefs on social identity. That is, climate change conspiracy beliefs may motivate people to identify with groups sharing similar conspiracy beliefs (i.e., identification with conspiracists). This motive can be particularly salient when the social belonging needs are being thwarted (e.g., being socially excluded). Importantly, ingroup identification can further motivate people to engage in pro-group behaviors (e.g., spreading climate change misinformation). We test this social identity perspective with two studies. In Study 1, with a three-wave longitudinal design, we found a longitudinal association between climate change conspiracy beliefs and identification with conspiracists, even after controlling for conspiracy mentality and national collective narcissism. In Study 2, we found that climate change conspiracy beliefs had a stronger positive association with identification with conspiracists among individuals who reported experiencing more social exclusion. Such ingroup identification was further related to a stronger intention to spread climate change conspiracy narratives. Overall, our results support the need to incorporate the social identity perspective into understanding the consequences of climate change conspiracy beliefs.