BACKGROUND AND OBJECTIVES: Obesity is a common chronic condition, and general practitioners are seeking more effective strategies for assisting their patients. The therapeutic relationship between patients and practitioners is increasingly recognised as a fundamental part of intervention effectiveness. The influence of therapeutic relationships in obesity interventions in primary care has not been systematically studied. We plan to undertake a systematic review and meta-analysis to identify the influence of the therapeutic alliance on the effectiveness of obesity interventions in primary healthcare. The aim of this article is to outline the study protocol. METHOD: A systematic review of primary care interventions for patients with obesity will be undertaken. Using Bordin's framework for the therapeutic alliance, interventions will be categorised as to whether they incorporate the alliance or not. A meta‑analysis will be performed if studies of sufficiently homogenous primary outcome data are found. DISCUSSION: Understanding the role of the therapeutic alliance on interventions for obesity management will have implications for both future intervention development and the translation of current interventions from trial settings to the real world.