Processes related to daily care of older adults during hospitalization, such as mobility and nutrition, have long-term consequences for their health and functioning. Although instrumental support provided by family members during hospitalization is highly prevalent, its relationship to older adults' actual walking and eating is unknown. Data on walking level (walking outside vs. inside the room) and nutritional intake were collected from 493 independent older adults admitted to internal medicine wards through up to three daily interviews using validated questionnaires. Informal support with walking and eating was assessed with the modified Informal Caregiving for Hospitalized Older Adults scale. Multivariate regression showed that informal support with walking and eating was associated with greater likelihood of walking inside the room and with lower nutritional intake. This association between informal support and less walking and eating call for routine functional assessments and tailored counseling of informal caregivers to meet older patients' support needs.