Land is the carrier of human economic activities, and its utilization has a profound impact on CO₂ emissions. With the advancement of urbanization, mixed land use has become a universal feature of cities. Analyzing the impact of mixed land use on CO₂ emissions is one of the prominent premises for coordinating urban development and the ecological environment. Using information entropy of land use structure (IELUS) to reflect its mixing degree, it was found that the relationship between IELUS and CO₂ emissions presents a positive U-shaped curve. Additionally, when IELUS is less than 0.351, they are negatively correlated, and vice versa. This means that cities can appropriately shift toward a higher degree of a mixed land use pattern to alleviate their environmental pressure. Further research shows that the spatial spillover effect will dilute the impact of mixed land use on CO₂ emissions. Meanwhile, improving production efficiency and increasing public transport travel are significant ways in a mixed land use model to reduce CO₂ emissions. Overall, this study provides a reference for the rational allocation of low-carbon land use systems.