Introduction: Increased mortality has been demonstrated in older adults with COVID-19, but the effect of frailty has been unclear. Methods: This multi-centre cohort study involved patients aged 18 years and older hospitalised with COVID-19, using routinely collected data. We used Cox regression analysis to assess the impact of age, frailty, and delirium on the risk of inpatient mortality, adjusting for sex, illness severity, inflammation, and co-morbidities. We used ordinal logistic regression analysis to assess the impact of age, Clinical Frailty Scale (CFS), and delirium on risk of increased care requirements on discharge, adjusting for the same variables. Results: Data from 5711 patients from 55 hospitals in 12 countries were included (median age 74, IQR 54 – 83; 55.2% male). The risk of death increased independently with increasing age (>80 vs 18-49: HR 3.57, CI 2.54 – 5.02), frailty (CFS 8 vs 1-3: HR 3.03, CI 2.29 – 4.00) inflammation, renal disease, cardiovascular disease, and cancer, but not delirium. Age, frailty (CFS 7 vs 1-3: OR 7.00, CI 5.27 – 9.32), delirium, dementia, and mental health diagnoses were all associated with increased risk of higher care needs on discharge. The likelihood of adverse outcomes increased across all grades of CFS from 4 to 9. Conclusions: Age and frailty are independently associated with adverse outcomes in COVID-19. Risk of increased care needs was also increased in survivors of COVID-19 with frailty or older age.Funding Statement: The Geriatric Medicine Research Collaborative has previously received funding from the British Geriatrics Society for administrative and running costs. No project specific funding was obtained for this research. MW and SR acknowledge support from the NIHR Newcastle Biomedical Research Centre.Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: Local, regional, and national approvals were obtained from all participating sites. In the UK, this study was registered as clinical audit or service evaluation, with approval granted in line with local information governance policies, in line with assessment and guidance by the Health Research Authority. At the lead site (University Hospitals Birmingham NHS Trust) this study was registered as clinical audit (CARMS-15986). In other countries, local principal investigators were responsible for obtaining approvals in line with their local, regional, and national guidelines and recommendations. Only routinely collected data was collected and patient care was not altered by this study. Anonymised data was securely transferred to the Birmingham Centre for Prospective and Observational Studies (BiCOPS), University of Birmingham via REDCap. All sites were required to confirm that approvals were in place prior to being provided with logins; written data sharing agreements were arranged where requested by individual sites.