[Objective] The spatiotemporal evolutionary characteristics and driving factors of coupling coordination between the carbon emission efficiency of cultivated land use and food security in the Fenhe River basin were explored, in order to provide decision-making references for improving the level of coupling coordination. [Methods] The undesired output super-efficiency SBM model and entropy weight method were used to measure the carbon emission efficiency and food security in the Fenhe River basin from 2005 to 2021. Next, the spatiotemporal characteristics were analyzed. On this basis, coupling coordination and its driving factors were discussed using the coupling coordination degree model and an optimal parameter-based geographic detector model. [Results] ① The carbon emission efficiency of cultivated land use varied significantly among counties; most counties still had mid-and low levels of efficiency. ② The level of food security in the Fenhe River basin showed a trend of “increase-decrease-increase.” The high-value areas were primarily concentrated in the northeast and southern regions, while the low-value areas were located mainly in the upper reaches of the Fenhe River basin, the urban area of Taiyuan City, and the gorge region of Linghuo Mountain. ③ The level of coupling coordination between carbon emission efficiency and food security in the Fenhe River basin was relatively low, showing a spatial distribution feature of “low in the upstream and high in the middle and lower reaches.” Counties in the stage of imbalanced degradation were mostly characterized by lagging carbon emission efficiency, while those in the phase of transitional development were chiefly characterized by lagging food security. ④ Per capita cultivated land area, urbanization rate, and population size were the primary driving factors affecting the level of coupling coordination between carbon emission efficiency and food security. [Conclusion] Counties in the Fenhe River basin should focus on differences, improve the short boards, and optimize cultivated land use while strengthening support for agricultural science as well as technological and policy-related guidance, ultimately achieving simultaneous and coordinated development of the two.