People with cognitive disability who have complex support needs typically engage with multiple services across social care domains that operate in silos. These services are individually ill-equipped to adequately recognise the presence or impact of disability and respond to the breadth, depth and intersectional nature of people's support needs. This lack of appropriate recognition and response often in turn works to further exacerbate the complexity of a person's support needs. This paper reports on a systematic review of current national and international evidence addressing good practice in supporting people with complex support needs. The review assesses evidence in policy and practice in disciplines including homelessness, child protection, disability, social work, youth studies, health, mental health and drug and alcohol to identify key factors that facilitate or hamper person-centred integrated social care. An analytic frame adapted from Ecological Systems Theory is deployed to present the key factors identified to shape responsive support at the level of people, services and systems. The paper concludes with a discussion of three key principles synthesised from the review as the crucial underpinnings of a responsive social care system for people with cognitive disability and complex support needs.