OBJECTIVES: To explore the cancer care experiences and unmet needs of people who identify as a sexual or gender minority. METHODS: A qualitative systematic review and meta-synthesis was undertaken based on a registered protocol. Following literature searching and study selection, study quality was examined using the Critical Appraisal Skill Programme Checklist. Qualitative data were extracted verbatim from included studies and synthesised using thematic analysis. RESULTS: Fifteen studies that included lesbian, gay and bisexual (LGB) people living with or beyond cancer were included in the review. Studies including gender minorities were not identified. The majority of study participants were sexual minority women with breast cancer or sexual minority men with prostate cancer. Meta-synthesis of 106 individual findings generated six overarching themes pertaining to sexual orientation disclosure, experiences and fear of homophobia, positive and negative healthcare professional behaviours, heterocentric systems and care, inadequacy of available support groups, and unmet needs for patient-centred care and LGB-specific information. LGB people often reported feelings of anxiety, invisibility, isolation and frustration throughout the cancer care continuum. CONCLUSIONS: Analysis of the experiences of LGB people with cancer care shows that LGB people face numerous challenges due to their sexual orientation and receive care that does not adequately address their needs. Training and education of healthcare professionals is strongly recommended to address some of these challenges and practice gaps. Culturally appropriate care includes avoiding heterosexual assumptions, use of inclusive language, the provision of tailored information and involving partners in care.