Teacher networks and communities have played an important role in teacher professional development. In such contexts, teachers often receive extensive feedback from peers as part of social learning. However, many teachers have difficulty identifying essential information from a large amount of peer feedback, which may impede self-reflection and peer learning. This study proposes the use of computer-assisted visual analytics of peer feedback to address this challenge. A visualisation-based analytical dashboard was designed and applied to help teachers analyse and reflect on peer feedback in a lesson study community for Technological Pedagogical Content Knowledge (TPACK) development. Primary school teachers participated in the lesson study, in which they collaborated to discuss lesson plans, observe recorded lessons, and give peer ratings and comments using an online platform. By comparing the performance between those using the analytical dashboard and others not using it, the results show that the approach has promising effects on improving teachers' TPACK as reflected in the lesson plans and their perceived confidence in TPACK. The implications of the findings are also discussed.