Previous research has found associations between classic psychedelic use and naturerelatedness, but the link between classic psychedelic use and human–animal relations remains largely unexplored. Using data representative of the US adult population, with regard to age, sex and ethnicity (N = 2822), this pre-registered study assessed lifetime classic psychedelic use, ego dissolution during respondents’ most intense experience using a classic psychedelic, and three measures related to human–animal relations: speciesism, animal solidarity and desire to help animals. The results showed that lifetime classic psychedelic use was negatively associated with speciesism (β = −0.07, p = 0.002), and positively associated with animal solidarity (β = 0.04, p = 0.041), but no association was found with desire to help animals (β = 0.01, p = 0.542). Ego dissolution during the respondents’ most intense experience using a classic psychedelic was negatively associated with speciesism (β = −0.17, p < 0.001), and positively associated with animal solidarity (β = 0.18, p < 0.001) and desire to help animals (β = 0.10, p = 0.007). The findings indicate that classic psychedelics and ego dissolution may have an impact on human–animal relations. As these results cannot demonstrate causality, however, future studies should use longitudinal research designs to further explore the potential causal link between classic psychedelic use and human–animal relations.