Background/Objective: Culturally adapted frailty screening tools are essential for improving health outcomes, facilitating clinical decision-making, promoting effective care planning, and ensuring accurate frailty assessment across diverse cultural contexts; their use among clinicians and academics is therefore supported. The purpose of this study was to assess internal consistency, test–retest reliability, and validity of the Arabic FRAIL scale (FRAIL-AR scale) for Arabic-speaking populations with colorectal cancer (CRC). Methods: This cross-sectional study included 137 participants diagnosed with CRC who completed the FRAIL-AR scale, the EORTC QLQ-C30 physical function subscale, and functional performance-based Timed Up and Go (TUG) and Five Times Sit-to-Stand (5xSTS) tasks. Internal consistency was assessed using Kuder–Richardson formula 20 (KR-20), and test–retest reliability was determined using the two-way random intraclass correlation coefficient ICC _(2.1). Convergent validity was evaluated by assessing the correlation between the FRAIL-AR scale against the EORTC QLQ-C30 physical function scale, TUG, and 5xSTS. Results: The FRAIL-AR scale exhibited good internal consistency (KR-20 = 0.80) and test–retest reliability (ICC _(2.1) = 0.89, 95% CI 0.77–0.94). Correlation analysis showed a weak negative correlation between the overall FRAIL-AR scale scores and EORTC QLQ-C30 physical function scale scores (r = −0.38, p < 0.05), while it exhibited a moderate positive correlation with TUG (r = 0.75, p < 0.01) and 5xSTS (r = 0.63, p < 0.01) scores. FRAIL-AR scores showed significant known-groups validity with higher frailty scores in older-age individuals (p < 0.01), females (p < 0.05), and those with comorbid conditions (≥5) (p < 0.05). Conclusion: The FRAIL-AR scale’s validity and reliability make it an appropriate tool for geriatricians, oncologists, and healthcare providers to evaluate and monitor frailty among Arabic-speaking colorectal cancer patients.