Background: The Inflammatory Bowel Disease-Disk (IBD-Disk) is a physician-administered tool that evaluates the functional status of patients with Inflammatory Bowel Disease (IBD). The aim of our study was to validate the content of the IBD-Disk in a Greek cohort of IBD patients. Methods: Two questionnaires [the IBD Disk and the IBD-Disability Index (IBD-DI)] were translated into Greek and administered to IBD patients at baseline visit, after 4 weeks and 6 months. Validation of the IBD Disk included measuring of concurrent validity, reproducibility, and internal consistency. Results: A total of 300 patients were included at baseline and 269 at follow-up. There was a good correlation between the total scores of the IBD-Disk and IBD-DI at baseline (Pearson correlation 0.87, p < 0.001). Reproducibility of the total IBD-Disk score was very good [intra-class correlation coefficient (ICC), 95% confidence interval (CI) 0.89 (0.86–0.91)]. Cronbach’s coefficient alpha for all items achieved 0.90 (95%CI 0.88–0.92), demonstrating a very good homogeneity of the IBD-Disk items. Female gender and extraintestinal manifestations were significantly associated with a higher IBD-Disk total score. Conclusions: The Greek version of the IBD-Disk proved to be a reliable and valid tool in detecting and assessing IBD-related disability in a Greek cohort of IBD patients.