The objective of this study was to evaluate the utilization of Online Mentoring system through Professional Learning Community with Information and Communication Technology via Cloud Computing for Pre-Service Teachers in Thailand. The sample was 26 pre-service teachers of computer education program, Faculty of Education, Phuket Rajabhat University of academic year 2018. The instrument was the evaluation form of system effectiveness in 4 components which were the ability of function requirement test; the accuracy of function test; the accessibility and simplicity of usability test; and the security test. The findings indicated that each element was at the highest level and the overall average was at 4.68; the Standard Deviation was 0.36. Therefore, it illustrated that online mentoring through professional learn was effective at the highest level.