: The COVID-19 pandemic resulted in rapid reorganisations of hospital care. In our hospital, the geriatrics team introduced the Clinical Frailty Scale (CFS) on the non-ICU COVID-19 units during these reorganisations. A retrospective analysis was performed to investigate the CFS as a risk factor for severe COVID-19 disease and in-hospital death in older patients with COVID-19. : In patients aged ≥70 years, an online geriatric assessment questionnaire was launched, from which the CFS was scored by the geriatrics team. Additional clinical data were collected from the electronic medical records. Risk factors related to ageing, such as the CFS, age-adjusted Charlson Comorbidity Index, living situation and cognitive decline, were examined alongside frequently reported risk factors in the general population. Outcomes were in-hospital death (primary outcome) and oxygen need of ≥6 litres and early warning score ≥7, as parameters for severe disease (secondary outcomes). Baseline characteristics were described with descriptive statistics. Associations were analysed with uni- and multivariable analyses. : One hundred and five patients were included, median age 82 years. CFS scores were 1-4 in 43, 5-6 in 45, and 7-9 in 17 patients. In multivariable analysis, CFS and cognitive decline were the only risk factors that were independently associated with in-hospital mortality. Chronic obstructive pulmonary disease, presence of respiratory symptoms on admission and male gender showed and independent association with severe disease. : A retrospective analysis shows that CFS and cognitive decline have added value for predicting in-hospital mortality in older patients with COVID-19 disease.