Ireland is experiencing a deepening homeless crisis with few sustainable solutions identified. This study explores front-line service providers’ experiences in their engagement with mental health services for adult service users who are homeless within the South-East Region of Ireland. Strauss and Corbin’s Grounded Theory approach was used to guide twenty in-depth interviews with front line service providers. Five key service gaps emerged: (1) inter-agency communication and collaboration; (2) assertive community recovery-orientated care; (3) training, information sharing and up-skilling; (4) building and sustaining trust, and (5) discharge planning and resource constraints. The findings suggest that the provision of bespoke tailored Mental Health Services, improved inter-agency collaboration and the development of relevant staff educational programmes are required. Further research to inform targeted service provision, policy and practice development is recommended.