Background There is some evidence that health and social care professional (HSCP) teams contribute to enhanced patient and process outcomes in increasingly crowded emergency departments (EDs), but the views of service users and providers on this model of care need investigation to optimize implementation. Objective This qualitative study investigated the perspectives of key ED stakeholders about HSCP teams working in the ED. Methods Using a participatory design, we conducted World Cafe focus groups and individual interviews in two Irish hospital sites with 65 participants (purposive sampling) including ED patients and carers/relatives, ED doctors and nurses, HSCPs and pre-hospital staff. Data were thematically analysed using NVivo software. Results Participants reported that ED-based HSCP teams could improve quality and integration of care and staff experience (Theme 1) and would be appropriate for older adults with complex needs and non-urgent complaints (Theme 2). Concerns were raised about operational and relational barriers to implementation (Theme 3), and changes in processes and culture were considered necessary for HSCPs to work successfully in the ED (Theme 4). In contrast to service providers, service users' concerns centred on the importance of positive communication and relations (Theme 5). Conclusions Our study indicates potential acceptability of HSCP teams working in the ED, especially to care for older adults; however, operational and relational aspects, particularly developing interdisciplinary and integrated care, need addressing to ensure successful implementation. Differences in priorities between service users and providers (relational vs operational) highlighted the usefulness of gathering views from multiple stakeholders to understand ED processes.