<p>In the face of global climate change, sustainable development has become a central challenge for all nations, demanding an effective balance between economic growth and environmental protection. As a critical link between human activities and carbon emissions, enhancing land use efficiency is of great significance for mitigation efforts. However, existing research has largely focused on single land use types, leaving a comprehensive understanding of the efficiency evolution across different land use types and their association with carbon emissions insufficient. This study constructs an evaluation framework covering agricultural land use efficiency (ALUE), construction land use efficiency (CLUE), and ecological land use efficiency (ELUE). It employs the Super-SBM model to measure the land use efficiency of 21 cities in Guangdong Province for the years 2000, 2010, and 2020. The study then reveals the spatio-temporal evolution of this efficiency using the natural breaks method and a transition matrix. Finally, it systematically analyzes the intrinsic relationship between land use efficiency and carbon emission intensity through correlation analysis. From 2000 to 2020, ALUE in Guangdong Province showed an overall upward trend. This was primarily attributed to the reduction in inputs such as pesticides and fertilizers and the stable growth of crop output, reflecting an optimization of agricultural land resource allocation to decrease carbon emission. Significant regional disparities were observed, with the highest efficiency in the Pearl River Delta and the lowest generally found in the Mountainous Region. The improvement of ALUE is significantly related to the reduction of carbon emission intensity, because the improvement of agricultural efficiency means the optimization of agricultural resource allocation. The change in CLUE followed a trend of initial decline followed by a rise. The early decline was attributed to the extensive use of construction land and high levels of undesirable outputs like wastewater and exhaust gases, while the subsequent rise was driven by the intensification of land use. The Pearl River Delta region exhibited the highest efficiency, whereas the Western Region was an area of low efficiency. The improvement in CLUE was also significantly correlated with a reduction in carbon emission intensity, demonstrating the important role of intensive and economical land use in emission reduction. In contrast, ELUE demonstrated a continuous downward trend during the study period, reflecting a lag in the improvement of ecosystem services. The Pearl River Delta region had the highest efficiency, while the Western Region had the lowest. Although improvements in ELUE showed a tendency to reduce carbon emissions, this relationship was not statistically significant. This could be related to factors such as landscape fragmentation and variations in the quality of ecological land, which affect the carbon sequestration capacity of ecosystems. Overall, the comprehensive LUE in Guangdong Province generally improved from 2000 to 2020. Spatially, the Pearl River Delta was significantly ahead, the Eastern Region was relatively balanced, and the Mountainous Region had the lowest overall efficiency. It is noteworthy that most high-efficiency cities transitioned from medium or lower efficiency levels. In conclusion, the carbon emission intensity in Guangdong Province decreased during the research period, a trend closely linked to green policies and economic transformation. This study suggests that enhancing agricultural and construction land use efficiency is significantly associated with lower regional carbon emission intensity.</p>