IntroductionWith the continuous expansion of higher education worldwide, the academic performance of first-generation college students has become an essential topic in the scope of international educational research. This study examines the impact of learning motivation (i.e., intrinsic and extrinsic motivation) and environmental support (i.e., instructional, relational, and campus support) on the academic outcomes of first-generation college students based on the Cultural Mismatch Theory and Self-Determination Theory from both individual and environmental perspectives.MethodsA two-stage stratified sampling strategy was adopted to guarantee that the samples were representative of the national populations of college students in mainland China. 87418 data were collected from the China College Student Survey (CCSS) 2020, among which 58,864 were first-generation college students. This study primarily employed descriptive statistical analysis and regression analysis methods.ResultsData analysis revealed that intrinsic learning motivation, relational support, campus support, and academic performance of first-generation college students are significantly lower than those of non-first-generation students. However, this study found no significant differences concerning external learning motivation and teaching support. Regression analysis showed that both learning motivation and environmental support positively predicted learning outcomes, with intrinsic learning motivation having the most substantial influence. Moreover, learning motivation and environmental support interact in jointly promoting the student’s academic success.DiscussionThis study highlighted that the academic development of first-generation college students results from the interplay between individual characteristics and the surrounding environment. Postnatal factors, particularly individual learning motivation, and institutional environment support, play a crucial role in their academic achievements.