Sexual minorities (individuals with a lesbian, gay, bisexual, queer, or other non-heterosexual identity) are at elevated risk of developing common mental health disorders relative to heterosexual people, yet have less favourable mental health service experiences and poorer treatment outcomes. We investigated the experiences of sexual minority service users accessing mental health services for common mental health problems (e.g. depression or anxiety) in the UK. We recruited 26 sexual minority adults with experiences of being referred to Improving Access to Psychological Therapies (IAPT) or primary care counselling services. Semi-structured interviews explored participants’ experiences of service use and views on service development. Interviews were analysed using thematic analysis. Barriers to effective relationships with practitioners included service users’ fears surrounding disclosure, and practitioners’ lack of understanding and/or neglect of discussions around sexuality. Regarding service development, participants highlighted the value of seeing practitioners with shared identities and experiences, visible signs of inclusivity, sexual minority training, tailored supports, and technological adjuncts. Our findings offer insights into possible contributory factors to treatment inequalities, and highlight potential methods for improving service provision for sexual minorities.