Introduction Patient falls in the hospital lead to adverse outcomes and impaired quality of life. Older adults with cancer who are frail may be at heightened risk of falls in the postoperative period. We sought to evaluate the association between degree of preoperative frailty and risk of inpatient postoperative falls and other outcomes among older adults with cancer. Materials and Methods We identified 7,661 patients aged 65 years or older who underwent elective cancer surgery from 2014 to 2020, had a hospital stay of ≥1 day, and had Memorial Sloan Kettering–Frailty Index (MSK-FI) data to allow assessment of frailty. Univariable logistic regression analysis was performed to evaluate the association between frailty and falls. Multivariable logistic regression analysis was performed to evaluate the composite outcome of 30-day readmission or 90-day death, with frailty, falls, and the interaction between frailty and falls as predictors; the analysis was adjusted for age, sex, race, and preoperative albumin level. Results In total, 7,661 patients were included in the analysis. Seventy-one (0.9%) had a fall, of whom eight (11%) were readmitted to the hospital within 30 days and seven (10%) died within 90 days. Higher MSK-FI score was associated with higher risk of falls (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.21–1.59]). The risk of falls for a patient with an MSK-FI score of 1 was 0.6%, compared with 1.7% for a patient with an MSK-FI score of 4. Poor outcome was associated with frailty (OR, 1.07 [95% CI, 1.02–1.13]) but not with falls (OR, 1.17 [95% CI, 0.57–2.22]). Discussion Preoperative frailty is associated with risk of inpatient postoperative falls and with other adverse outcomes after surgery among older adults with cancer. Screening for frailty in the preoperative setting would enable healthcare institutions to implement interventions aimed at reducing the incidence of inpatient postoperative falls to reduce fall-related adverse events.