The implementation of online teaching and assessments was prompted by the current COVID-19 pandemic. Therefore, all universities had to adopt the distance-learning method as the only choice to continue education delivery. This study's main objective is to understand the effectiveness of assessment techniques followed through distance learning in Sri Lankan management undergraduates during COVID-19. Furthermore, utilizing a qualitative approach and thematic analysis for data analysis, semi-structured interviews with 13 management faculty lecturers selected through the purposive sample technique were used for data collection. The survey was conducted via an online questionnaire that was distributed to Sri Lankan undergraduates, and a total of 387 samples from management undergraduates were drawn for the quantitative data analysis using a simple random sampling technique. The study's main findings revealed that five online assessments are currently being utilized to evaluate management undergraduates' academic performance under distance learning, including online examinations, online presentations, online quizzes, case studies, and report submissions. In addition, this study statistically and with some qualitative empirical evidences in the existing literature proved that online examinations, online quizzes, and report submissions have a significant impact on undergraduates' academic performance. Further, this study also recommended that universities should implement procedures for online assessment techniques in order to assess the quality assurance of assessment techniques.