The aim of the study was to develop a cost-effective form of online proctoring mechanism that can serve as a scalable and secure solution to cater to high-stake assessments in institutions, with a particular focus on attaining high levels of flexibility and user-friendliness. With reference to existing systems, a self-proctored mechanism is proposed to conduct proctoring online assessment with a convenient setup by students. Students were guided to record and submit recordings from their webcam and captured from their computer screens. The recording submission compliance level and statistics were evaluated to gauge the effectiveness of the mechanism. The devised mechanism was deemed reliable across various student groups tested in two lower-division undergraduate courses with total enrolment of over 600 students. With the advantages and potential improvements in conducting assessments online identified, the devised mechanism can provide a satisfactory baseline for the future development of large-scale high-stake assessment.