(1) Background: This study explores the intricate relationship between sports and the environment, underscoring the influence of individual awareness of climate change consequences on fostering eco-friendly behavior among sports spectators. (2) Methods: The research introduces an extended theory of planned behavior model, incorporating climate change awareness. Analyzing data from 431 participants at US professional sports events, the study measured variables like climate change awareness and theory of planned behavior constructs. (3) Results: Sequential multiple mediation analysis validated the model, revealing that climate change awareness positively predicts the intention to reduce single-use plastics in the context of sport spectatorship. This relationship was partially mediated by theory of planned behavior variables, with subjective norms identified as a crucial explanatory factor. (4) Conclusions: The study’s originality lies in shedding light on pro-environmental intentions within sports spectatorship. Its insights provide foundational knowledge for researchers and organizations aiming to devise sustainability strategies in the realm of sports.