Marginalised communities such as homeless people, people who use drugs (PWUD), lesbian, gay, bisexual, transgender and intersex people (LGBTI), prisoners, sex workers and undocumented migrants are at high risk of poor health and yet face substantial barriers in accessing health and support services. The Nobody Left Outside (NLO) Service Design Checklist aims to promote a collaborative, evidence-based approach to service design and monitoring based on equity, non-discrimination and community engagement.