This research aimed to develop the moral responsibility of Grade 9 students through active learning on an online platform to achieve the requirement for at least 70% of the standard. The students who participated in this research were thirty-two students of Grade 9 students who were studying in the second semester of the academic year 2021 from a secondary school, Chaingyuen Pittayokhom School, in Maha Sarakham Province, Thailand. Eight lesson plans for active learning in the context of genetic inheritance for a total of 12 h were employed. Four aspects of moral responsibility, specific responsibility towards oneself, responsibility for performing duties and assigned tasks, responsibility for their actions, and responsibility towards others were evaluated using the observation and interview approach according to the standard IOC.The research findings revealed that over all, the moral responsibility of the students was at a moderate level with a total average score of 38.69, representing 64.48% for the first spiral of learning organization and at a moderately high level with the total average score of 49.31, representing 82.19% for the second spiral of the learning organization.The results obtained from this research obviously indicate that the active learning on the online platform is a suitable format to develop the moral responsibility of the students with a satisfactory achievement and can be applied to other learning managements.