Abstract: Constructing low-carbon and livable new cities is a new concept and trend in urban development. Simultaneously addressing low-carbon emissions and improving climate adaptability in urban planning and construction is crucial. This approach plays a key role in mitigating the impacts of climate change during urbanization and enhancing the overall quality of urban life. This study focuses on the Chongqing Economic and Technological Development Zone as the experimental area and applies linear programming to optimize the land use structure considering low-carbon goals for 2025. A micro-scale numerical model was used to simulate changes in the wind–thermal environment in the experimental area for both January and July 2025, following the optimization of land use for low-carbon and spatial efficiency. The results indicate the following. (1) After optimizing the land use structure for low-carbon goals, the experimental area reduced carbon sources, such as construction land, while increasing carbon sinks, such as forests. This led to a 12.1% reduction in total annual land carbon emissions, approximately 19.0 × 10⁴ tons. (2) The combination of low-carbon and spatial optimization improved the ventilation environment in the experimental area. In January and July, the average wind speeds increased by 0.7% and 1.5%, respectively, with local maximum increases of 8.0% and 11.0%. The average wind speed increased at 73.5% and 79.3% of the locations, and an observed increase in average wind speed occurred at 11 and 20 time points in the daily hourly sequence, respectively. The urban heat island effect showed signs of alleviation, and average temperatures in January and July decreased by 1.3% and 0.7%, respectively, with maximum localized decreases of 13.2% and 5.0%. Average temperatures dropped at 76.3% and 76.2% of the locations, and all time points in the daily hourly sequence showed a decrease in average temperature. Optimizing the urban land use structure for both low-carbon and spatial efficiency has the potential to simultaneously reduce carbon emissions, improve the wind–thermal environment, and enhance urban climate adaptability. This study provides valuable insights for formulating goals related to Chongqing’s economic and social development planning and overall urban planning indicators.