Contemporary educational research has increasingly highlighted the necessity and significance of online education and its effects on student engagement and academic success. However, it's noteworthy that there is still a gap in the growing literature regarding the student-related factors that influence individuals' engagement and achievement in online education. This study sought to investigate the effects of students' online learning readiness in online learning engagement with the mediating role of academic resilience in this relationship. A cross-sectional survey design was employed based on the data from a total of 3550 undergraduates studying at state universities in six provinces across the eastern, central, and western regions of Türkiye. Structural equation modeling was conducted to estimate the complex relationships proposed in the model through AMOS 26. The findings demonstrated that students' online learning readiness has a moderate but statistically significant direct effect on engagement in online learning, as well as had a significant and moderate effect on academic resilience. Furthermore, the results indicated that academic resilience plays a crucial role as a significant mediator in the relationship between students' online learning readiness and online learning engagement. The current study also confirmed the conceptual model built on the variables that have notable impacts on students' academic achievement. This research, one of the first in its field, furnishes empirical evidence on a conceptualized set of relationships and offers insights for policy makers, curriculum developers and practitioners to consider the significant student-related factors in terms of design, development, and delivery of online courses.