Background Mental health has gained prominence as a global public health priority. However, a substantial treatment gap persists in many low- and middle-income countries. Within this scenario, the nexus between homelessness, poverty and mental illness represents a particularly complex issue. This article presents the experience of The Banyan, a 25 years old non-profit organisation providing mental health care to people living in poverty in Tamil Nadu, India. Case presentation The case study describes the evolution of The Banyan using a timeline narrative. By applying an action learning framework, the organisation’s evolution through four lifecycles, strategy and the key elements underlying mental health system responses are identified and presented. ‘User centred’ and ‘service integration’ emerge as the main dimensions of The Banyan’s responsive health system. Relating to these two attributes, a typology of services is derived, indicating the responsiveness of mental health systems in addressing complex problems. The role of the organisational culture and the expressed values during the transition is considered. Conclusions The case study serves as an example of how responsive mental health systems may be constructed with both a user centred and a service integration focus.