Background: Formative assessments build a positive learning environment and provide feedback to enhance learning. This study examined the impact of online formative and low-stake summative assessments on medical students' learning outcomes in the Clinically Oriented Anatomy course from 2016 to 2020. We aimed to demonstrate that formative assessments clarify exam expectations, decrease test anxiety, and facilitate the early identification of academically at-risk students, enabling timely academic counseling and guidance. Methods: Students completed seven formative and nine low-stake summative assessments. Results: Strong correlations were observed between formative and summative exams performance (Spearman's rho (r[subscript s]) = 0.60-0.72) and between summative exams and NBME performance (r[subscript s] = 0.70-0.77). A multivariable model identified students scoring below 75% on the unit 1 summative exam as academically at-risk. While this model effectively identified students who were not at risk, at-risk students consistently underperformed on early assessments compared to those who achieved high pass or honors grades. Over 90% of students reported that formative assessments clarified exam expectations, reduced test anxiety, and improved exam performance. Conclusions: Over 4 years, formative assessments enhanced learning outcomes, clarified examination expectations, and reduced student stress. Online formative assessments are valuable for the early identification of at-risk students, allowing timely interventions, such as academic counselling and remediation, to improve student learning experience.