As nurses in hospitals are confronted with increasing numbers of older patients, their geriatric nursing skills and knowledge must be integrated into daily clinical practice. Early risk identification via screening tools may help improve geriatric care. To reduce the assessment burden of nurses, the Maastricht Frailty Screening Tool for Hospitalized Patients (MFST-HP) was developed. The aim of the current study was to explore aspects of reliability, validity, and feasibility of the MFST-HP. Intrarater reliability was assessed by measuring patients two times within 24 hours. Interrater reliability was assessed by having patients screened by two different nurses. Construct validity was studied by the associations between the MFST-HP scores and age and comorbidities. Intraclass correlation coefficients for both intra-and interrater reliability were good (>0.93). Older patients and those with more comorbidity showed higher scores on the MFST-HP compared to younger patients and those with less comorbidity. The MFST-HP shows promise as a reliable, valid, and feasible screening tool for frailty among hospitalized older adults.