Abstract Background There is limited understanding of the contribution made by older people and their caregivers to acute healthcare in the home and how this compares to hospital inpatient healthcare. Objectives To explore the work of older people and caregivers at the time of an acute health event, the interface with professionals in a hospital and hospital at home (HAH) and how their experiences relate to the principles underpinning comprehensive geriatric assessment (CGA). Design A qualitative interview study within a UK multi-site participant randomised trial of geriatrician-led admission avoidance HAH, compared with hospital inpatient care. Methods We conducted semi-structured interviews with 34 older people (15 had received HAH and 19 hospital care) alone or alongside caregivers (29 caregivers; 12 HAH, 17 hospital care), in three sites that recruited participants to a randomised trial, during 2017–2018. We used normalisation process theory to guide our analysis and interpretation of the data. Results Patients and caregivers described efforts to understand changes in health, interpret assessments and mitigate a lack of involvement in decisions. Practical work included managing risks, mobilising resources to meet health-related needs, and integrating the acute episode into longer-term strategies. Personal, relational and environmental factors facilitated or challenged adaptive capacity and ability to manage. Conclusions Patients and caregivers contributed to acute healthcare in both locations, often in parallel to healthcare providers. Our findings highlight an opportunity for CGA-guided services at the interface of acute and chronic condition management to facilitate personal, social and service strategies extending beyond an acute episode of healthcare.