Frailty is associated with poorer health-related quality of life (HRQoL) in older adults, but studies rarely assess general and oral HRQoL concurrently in acute care populations. Objectives: To examine the associations between frailty and general as well as oral HRQoL among older adults admitted to a municipal in-patient acute care (MipAC) unit. Design: Cross-sectional study. Setting: Oslo MipAC unit, Norway. Participants: A total of 382 patients aged 70 years or older admitted to the MipAC unit between January and September 2023. Measurements: Frailty was assessed using the Clinical Frailty Scale (CFS). General HRQoL was measured with the 15D instrument and a single-item global life satisfaction question. Oral HRQoL was assessed using the Oral Health Impact Profile-14 (OHIP 14). Associations between frailty and HRQoL were analyzed using linear, ordinal logistic, and binary logistic regression. Exploratory analyses of 15D and OHIP-14 dimensions were performed using non-parametric trend tests. Results: Increasing frailty was significantly associated with lower 15D scores (adjusted B -0.053, 95% CI -0.061 to -0.045), higher odds of lower life satisfaction (adjusted OR 1.19, 95% CI 1.02 to 1.39), and higher odds of reporting oral health impacts on the OHIP-14 (adjusted OR 1.25, 95% CI 1.05 to 1.48). Most 15D dimensions declined with increasing frailty, except distress. For OHIP-14, significant associations were observed for functional limitation, physical pain, and psychological disability. Conclusions: Frailty assessed with the CFS was consistently associated with reduced general and oral HRQoL in older adults admitted to a MipAC unit. These findings support the clinical relevance of simple frailty assessment during acute admission and suggest that it may help identify patients at risk of poorer quality of life.