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Background The number of people identifying as transgender and nonbinary has increased substantially in recent years. Whilst mental health has been studied extensively, physical health outcomes and health risk behaviours of transgender people are much less understood. We aimed to provide an overview of non-communicable health outcomes and health risk behaviours by conducting an umbrella review of systematic reviews.Methods Following a pre-registered protocol (PROSPERO: CRD42023449644), we searched Embase, Medline and PsychINFO databases from inception to 21st August 2023 to identify systematic reviews which addressed non-communicable diseases and health risk behaviours. Reviews were screened by two reviewers and pre-specified data extracted. Quality appraisal was performed using AMSTAR2. Data were synthesised by health outcome using forest plots, effect direction plots and narrative summary.Results Of 7496 records screened after the removal of duplicates, 46 met the inclusion criteria and 31 systematic reviews were synthesised after accounting for reviews containing overlapping primary studies. fourteen reviews addressed health risk behaviours, twelve cardiovascular outcomes, nine cancer and three each for bone health and diabetes. Only one review addressed chronic respiratory diseases. Quality appraisal was critically low for 26 reviews, low for four reviews and high for only one review.Cardiovascular diseases were more common in transgender women compared to cisgender men, cisgender women and transgender men, with cardiovascular mortality also being higher. Most cancers were more common in transgender men than cisgender men, with rates of cancer and brain tumours also higher compared to cisgender women. Breast cancer was more common in transgender men and transgender women than cisgender men but less common than cisgender women. Bone mineral density did not differ substantially across genders or when comparing pre- and post-hormone replacement therapy (HRT) Transgender people had higher odds of lifetime substance use and tobacco use compared to cisgender people. Common methodological issues identified by systematic reviews included inadequate statistical power, limited data on nonbinary people and lack of comparator groups.Conclusion Existing systematic reviews report higher risks of several non-communicable diseases and their risk factors among transgender (compared to cisgender) people, but the quality of the existing evidence base is poor. Lack of standardised reporting limited our ability to quantitatively synthesise data, with our umbrella review only able to describe broad epidemiological patterns. Future research should address knowledge gaps for nonbinary people and those in low- and middle-income countries, but action to improve physical health of transgender people is warranted now.