Objectives The aim of this study was to identify current physical health guidelines for severe mental illness (SMI) and appraise them using the Appraisal of Guidelines for Research and Evaluation (AGREE) II Instrument. Methods Relevant research databases and grey literature were systematically searched to identify physical health guidelines for people with SMI. The grey literature was explored by web searches and targeted searches of the English websites of relevant peak bodies and government health agencies from Organisation for Economic Co-operation and Development countries. Included guidelines were independently appraised by two authors (NF and JH) using the AGREE II Instrument. Results Of the 5352 records screened, 33 were assessed for eligibility. Fifteen practice guidelines met the inclusion criteria. The median domain scores as rated by the AGREE II Instrument ranged from 17% to 69%. The World Health Organization guideline, which demonstrated a broad range of clinical recommendations and sound methodological rigour, was rated the best. Conclusions Most guidelines scored poorly when rated by the AGREE II Instrument. However, these guidelines may still be useful in assisting evidence-based clinical practice. The methodological rigour of future guidelines can be improved by ensuring the AGREE II domains are addressed during the development phase. What is known about the topic? Compared with the general population, people with SMI experience greater chronic disease morbidity and mortality. There is limited evidence from randomised controlled trials to guide physical health care monitoring for people with SMI. Current guidelines and practice are largely based on expert consensus, clinical experience and good intentions. What does this paper add? Using the AGREE II Instrument, this paper appraises the current physical health guidelines for people with SMI. The attributes of the guidelines examined included the evidence base, clarity of presentation, applicability in the real world, the involvement of stakeholders and conflicts of interest of various parties involved in guideline development. What are the implications for practitioners? This review highlights the scarcity of high-quality and evidence-based guidelines for clinicians and researchers to address the physical health of people with SMI.