Objective: The coronavirus disease 2019 (COVID-19) pandemic accelerated the shift towards online learning in psychology higher education. It is important to investigate the factors that impacted student success in online learning, both in preparation for future emergencies in education, and to investigate the drivers of online course engagement in general. This study aims to identify factors impacting students’ online academic behaviors and success by testing an integrated social cognition model. Method: A sample of 279 psychology undergraduates from an Australian university completed surveys at the beginning and mid-point of a 12-week term, and had their academic behaviors and final grades assessed via registrar data. Results: Structural equation modeling revealed that attitudes and perceived behavioral control predicted intention and, indirectly, course grades via intention, planning, self-monitoring, and academic behaviors. Intentions predicted academic behaviors through planning and self-monitoring, and course grades via lecture attendance and worksheet completion, but not tutorial attendance. Baseline habit predicted follow-up habit, which influenced lecture attendance, tutorial attendance, and worksheet completion, and indirectly predicted course grades via lecture attendance. Conclusions: Results highlight that motivational, volitional, and nonconscious variables significantly contribute to psychology students’ online academic behaviors and success. Future research should explore interventions targeting these processes to enhance higher education.