Abstract: Exploring the spatial and temporal evolution characteristics of cultivated land conversion and its driving mechanism is the premise of cultivated land protection. The spatial and temporal evolution characteristics and driving mechanism of cultivated land conversion in Lower Liaohe Plain from 2000 to 2020 are analyzed, which provides a theoretical basis for the formulation of cultivated land protection policies and the prevention of cultivated land conversion in this area. Using land-use and socio-economic data from 5 years (2000, 2005, 2010, 2015, and 2020) of the study area, we employed ArcGIS 10.2 spatial overlay analysis to calculate the area and percentage of cultivated land conversion in Lower Liaohe River Plain. Statistical and geographic information system methods, such as the gravity center migration model, kernel density analysis, and geographical detectors, were employed for spatial analysis. The results revealed that from 2000 to 2020, there were cyclical fluctuations in the area and rates of agricultural land conversion in Lower Liaohe River Plain. Moreover, we found that cultivated land with a total area of 2201.52 km² had undergone conversion, indicating a conversion rate of 7.11%, with most of the conversion occurring in the vicinity of Shenyang City. The converted land mainly transitioned to urban and rural residential area, and other construction land, with conversion to rural residential land accounting for the highest proportion. Spatially, during the study period, the gravity center of converted cultivated land shifted from Liaozhong District to Yuhong District, representing a distance of 83.17 km. The conversion of cultivated land was found to show spatial agglomeration characteristics, with agglomeration mainly observed in Hunnan, Sujiatun, Shenbei, and Yuhong, and the surrounding areas, being characterized by a concentrated pattern toward the east and dispersion toward the west. With respect to the factors driving this conversion of cultivated land, single factor analysis revealed that the impact levels of the non-agricultural factors influencing such conversion were as follows: total power of agricultural machinery > registrated population > urban population > investments in fixed asset > added value of the tertiary industry > GDP > grain output > added value of the secondary industry. This ranking indicates that advances in agricultural technology and demographic changes are the key factors influencing the cultivated land conversion, whereas economic and industrial factors act as direct drivers. Two-factor analysis further revealed an two-factor enhancement or non-linear enhancement, highlighting that multiple factors collectively influence the cultivated land conversion rather than single factors acting independently. In summary, the cultivated land conversion is a complex process driven by the interplay of societal and economic factors, resulting in a dynamically evolving spatial phenomenon. On the basis of our findings, we recommend that such land conversion should be managed by applying strict regulations on the scale of land converted for urban purposes, maximizing the utility of rural residential areas, transforming economic development models, and promoting changes in the agricultural industrial structure.