Acute health care use varies by age, with older adults the highest users of acute health care services. Using data from The Irish Longitudinal Study on Ageing (TILDA), the aim of this study was to investigate the association between acute health care utilization (emergency department [ED] visit with or without hospitalization) at baseline and subjective and objective measures of function measured at 4-year follow-up. This study represents a secondary analysis of a prospective cohort study, where data from Wave 1 (baseline) and Wave 3 of TILDA were analyzed in conjunction with a public and patient involvement group of older adults. Acute health care utilization was defined as an ED visit with or without hospitalization in the previous 12 months. Function was assessed objectively using the Timed Up and Go (TUG) test and a measure of grip strength, and subjectively using self-report limitations in activities of daily living (ADL) and instrumental ADL (IADL). A total of 1 516 participants met the study inclusion criteria. Mean age was 70.9 ± 4.6 years and 48% were male. At baseline, 1 280 participants reported no acute health care use. One hundred and eighteen indicated an ED visit but no hospitalization in the previous 12 months and 118 reported both an ED visit and hospitalization. Adjusting for all covariates, compared to those with no acute health care utilization, those with an ED visit with no hospital admission had poorer TUG performance at follow-up (β = 0.67, 95% confidence interval: 0.34, 1.29, p = .039). This paper supports previous research that acute health care events, specifically ED usage, are associated with reduced function for older adults as assessed by TUG at follow-up. No associations were observed for grip strength, ADL, or IADL. Further research is required in this area, exploring ED visits and the possible benefits of evaluating older adults at this stage.