Online peer assessment has been proposed as an effective strategy for cultivating critical thinkers in higher education, but there is a dearth of relevant studies in a Confucian heritage context. This study investigated the effects of online peer assessment in a General Education course on the development of critical thinking among Hong Kong undergraduates, with a design characterised by six elements (i.e. online peer assessment training, provision of guiding questions, peer feedback requirements, anonymity, student evaluation of the usefulness of peer feedback and summative use of online peer assessment). Analysis of the participants' e-journal entries revealed a significant improvement in critical thinking in the experimental groups. Individual follow-up interviews indicated that the participants acknowledged online peer assessment design with the consideration of cultural influence and at the same time made some suggestions for refinement. This study highlights the need to adopt a culturally embedded approach to design online peer assessment to cultivate students' critical thinking in non-western contexts. Copyright © 2021 Routledge.