Background: Although age is often used as a clinical risk stratification tool, recent data have suggested that adverse outcomes are driven by frailty rather than chronological age. Aims: In this nationwide cohort study, we assessed the prevalence of frailty, and factors associated with 30-day readmission and mortality among hospitalized IBD patients. Methods: Using the Nationwide Readmission Database, we examined all patients with IBD hospitalized from 2010 to 2014. Based on index admission, we defined IBD and frailty using previously validated ICD codes. We used univariable and multivariable regression to assess risk factors associated with all-cause 30-day readmission and 30-day readmission mortality. Results: From 2010 to 2014, 1,405,529 IBD index admissions were identified, with 152,974 (10.9%) categorized as frail. Over this time period, the prevalence of frailty increased each year from 10.20% (27,594) in 2010 to 11.45% (33,507) in 2014. On multivariable analysis, frailty was an independent predictor of readmission (aRR 1.16, 95% CI: 1.14–1.17), as well as readmission mortality (aRR 1.12, 95% CI 1.02–1.23) after adjusting for relevant clinical factors. Frailty also remained associated with readmission after stratification by IBD subtype, admission characteristics (surgical vs. non-surgical), age (patients ≥ 60 years old), and when excluding malnutrition, weight loss, and fecal incontinence as frailty indicators. Conversely, we found older age to be associated with a lower risk of readmission. Conclusions: Frailty, independent of age, comorbidities, and severity of admission, is associated with a higher risk of readmission and mortality among IBD patients, and is increasing in prevalence. Given frailty is a potentially modifiable risk factor, future studies prospectively assessing frailty within the IBD patient population are needed.