Objectives: The purpose of the study was to cross-culturally adapt the Rapid Assessment of Physical Activity (RAPA) for Arabic speaking people and examine the test-retest reliability and the construct validity in Saudi older adults. Methods: Test-retest reliability was assessed over two testing visits occurring one week apart. The construct validity was examined between RAPA and Short Physical Performance Battery (SPPB) and Timed Up and Go (TUG) tests. Results: The original RAPA was translated into Arabic following standardized guidelines. For the test-retest reliability, the weighted kappa was 0.87 (95% confidence interval: 0.76–0.98), which indicates good reliability. There was a significant correlation between the Arabic version of RAPA and the SPPB (Spearman's correlation coefficients (r) = 0.536, p < 0.001), and the TUG test (r = -0.435, p < 0.010). Conclusions: The Arabic version of the RAPA questionnaire adapted for Saudi older adults provides an easy, valid, and reliable way to measure physical activity