INTRODUCTION: Mild cognitive impairment (MCI) and dementia impose a significant burden on individuals and their caregivers. Dyadic psychosocial education, which treats care recipients and their caregivers as a pair of active participants, has the potential to improve health outcomes for people with cognitive impairment and their caregivers. However, the results of recent studies on this subject are contradictory. We aim to evaluate the effectiveness of dyadic psychosocial education for people with MCI or dementia and their informal caregivers. METHODS AND ANALYSIS: Six databases will be searched. We will include all randomised controlled trials that compare dyadic psychosocial education to usual care. The risk of bias will be assessed using the Cochrane Risk-of-Bias Assessment Tool (V.2). Meta-analyses, subgroup analyses and sensitivity analyses will be performed using Stata V.15.1. A narrative synthesis will be conducted if quantitative analysis is not feasible. ETHICS AND DISSEMINATION: This study and subsequent systematic review will not collect individual-level data and, therefore, do not require ethics committee approval. Peer-reviewed publications will disseminate the study results. PROSPERO REGISTRATION NUMBER: CRD42024497554.