Chemsex is a pattern of using specific drugs with the intent of enhancing the sexual experiences of men who have sex with men. Chemsex participation is oftenmotivated by a desire for community connection or enhanced sexual pleasure. Many individuals who participate in chemsex can mitigate much of the associated risk and report limited, if any, harm. However, for some, chemsex can be problematic, precipitating or exacerbating mental health issues. Despite increasing amounts of research into chemsex, there is no consensus about how to best support people who participate in chemsex when they present for psychological therapies. In the absence of specific clinical guidelines, this paper explores the intersection of chemsex and mental health problems. Principles of affirming and non-stigmatising, assessment, formulation, and intervention strategies are discussed, and recommendations are made throughout. Drawing on contemporary evidence, we present cognitive behavioural approaches to supporting service users who participate in chemsex with anxiety, depression, and post-traumatic stress disorder. By enhancing cultural safety and tailoring existing evidence-based treatments, therapists can improve engagement and outcomes for individuals who engage in chemsex. We recommend an inclusive approach that champions service user choice, paired with a sensitive, sex-positive, and trauma-informed perspective. Therapists within Talking Therapy services are well placed to support service users who participate in chemsex and have co-occurring mental health difficulties.