Although online learning systems (OLSs) are widely discussed with regard to most forms of higher education, they are still immature in terms of their development and compared to mainstream teaching and learning activities, and their implementation remains a challenge. Few studies have investigated the factors that contribute to students' learning performance in the context of the adoption of OLSs in higher educational institutions. Additionally, among the handful of studies that focus on this research issue, investigating the influences of environmental factors and personal innovativeness on students' learning performance and adoption of OLSs has received very little attention. Consequently, by integrating social cognitive theory and innovation diffusion theory, this study developed a theoretical model of OLS adoption. It empirically validated the model using data collected from 151 undergraduate students who used OLSs. The results showed that key compatibility (as an environmental factor) and personal innovativeness (as a personal factor) had significant direct and/or indirect influences on students' learning performance and continued intentions to use OLSs. Theoretical and practical implications are also discussed.