Background: We examined the association between restless legs syndrome (RLS) and comprehensive geriatric assessment (CGA) data in two older European populations. The second goal was to evaluate correlates of their quality of life (QoL). Methods: Diagnostic criteria of the International RLS Study Group (IRLSSG) and elements of CGA were used in this study. Results: Among the examined 246 participants, 77 (31.3%) suffered from RLS, more often in the UK (39.4%) than in Poland (25.4%) (p = 0.019). In the multivariate logistic regression model, female sex [OR (CI) = 3.29 (1.51–7.21); p = 0.0014], the number of medications per day [OR (CI) = 1.11 (1.02–1.20); p = 0.011] and alcohol consumption [OR (CI) = 5.41 (2.67–10.95); p < 0.001] increased the probability of RLS. Residing in Poland [OR (CI) = 3.06 (1.36–6.88); p = 0.005], the presence of RLS [OR (CI) = 2.90 (1.36–6.17); p = 0.004], chronic heart failure, [OR (CI) = 3.60 (1.75–7.41); p < 0.001], osteoarthritis [OR (CI) = 2.85 (1.47–5.49); p = 0.0016], and urinary incontinence [OR (CI) = 4.74 (1.87–11.9); p < 0.001] were associated with a higher probability of mobility dimension problems in the QoL. Higher physical activity was related to a lower probability of mobility problems [OR (CI) = 0.85 (0.78–0.92); p < 0.001]. Conclusions: female sex, the number of medications and alcohol consumption are independent correlates of RLS in older adults. RLS together with several chronic medical conditions and a low physical activity level were independent correlates of the mobility dimension of the QoL.