This conceptual paper discusses 'unseen observation' as an alternative model of classroom observation to support teachers' professional learning. The paper starts with a critical synopsis of how observation has been appropriated principally as a performance management tool for monitoring teacher effectiveness in the UK. It argues that the overreliance on assessment-based models has led to the hegemony of observation as a performative tool and its subsequent dilution as a catalyst for professional learning to develop teachers' pedagogic thinking and practice. As a counter narrative, this paper proposes an alternative, peer-based model, unseen observation, which reconceptualises and reconfigures observation for professional learning by prioritising collegial meaning-making and reflexive dialogue. Drawing on the concept of intersubjectivity to theorise unseen observation, the principles, purpose and practical application of this model are discussed, along with its benefits and challenges. The paper argues that unseen observation offers a structured approach for stimulating and channelling opportunities for teachers to engage in honest introspection, participatory sensemaking and reflexive dialogue of their practice. Meaningful and sustainable improvements in professional learning are arguably more likely to flourish by creating such opportunities, though further research is needed to investigate the application and impact of unseen observation as a model.