Stewart is an academic GP who has extensively researched the inverse care law, and how this manifests in general practice. He is a founding member of the Scottish Deep End Project which has since grown into an international movement. Stewart is also internationally recognised for his work in multimorbidity and health inequalities, including researching the importance of empathy in health care interactions. He developed the Consultation and Relational Empathy (CARE) measure which is now used in over 40 countries around the world. He has published almost 400 scientific papers, in leading medical journals including the Lancet and the BMJ.