With increasing need to achieve appropriate balance between learning support and self-regulation within the context of online learning, formative feedback has been identified as a viable means to achieve meaningful engagement. Specifically, this study sought to establish how peer-peer formative feedback was facilitated in an online course and to what extent this engaged students in meaningful learning experiences. This case study entailed an in-depth investigation into the design and implementation of an online course in a New Zealand university. The studied course was part of a postgraduate programme in continuing (in-service) teacher education. The study adopted a case study methodology with a bias on qualitative techniques. Online observations, analysis of the archived course discourse and interviews were utilised as sources of data. The data from multiple sources were subsequently triangulated to corroborate the evidence. The findings indicate that peer formative feedback promoted active learners' participation and meaningful engagement. The findings further showed that opportunities for dialogic peer formative feedback promoted learning support and self-regulation.