ObjectivesTo explore adult stakeholders' perspectives on what supports or undermines the mental health of sexual and gender minoritised adolescents (SGMA) in everyday life in order to better understand how to foster supportive psychosocial environments for SGMA.DesignDescriptive qualitative study design, using framework analysis.MethodsSemi‐structured interviews were conducted remotely with 16 UK‐based adult stakeholders which included parents of SGMA, health and social care professionals, community‐based professionals, and professionals who commission services related to adolescent health and well‐being.ResultsNine themes were identified that represented barriers and enablers of fostering psychosocial environments that are supportive of SGMA mental health. Example barrier themes include SGMA ‘facing chronic and acute safety threats and stress’, ‘psychological responses to social connection losses and navigating alienation’, ‘digital exposure and online risk and vulnerability’ and ‘conflicting messages, resulting divisions and adult distancing’. Example enablers include ‘exploring, owning, and changing (personal) identities’, ‘advocating alongside adolescents whilst containing oneself as the adult in the situation’ and ‘personally fostering adolescents’ psychological safety and inclusion’.ConclusionsAdult stakeholders report that SGMA are often exposed to environments hostile to key aspects of their identity which then by extension undermines their mental health. These experiences can threaten their sense of safety and evolving identity. Practitioners in particular should be aware of the stressors relating to SGMA identity and minoritisation experiences in order to develop the psychological safety and sense of inclusion needed for SGMA to trust in the relationship and the support offered.