Background: The very low physical fitness levels of people with intellectual disabilities (ID) may influence their life expectancy. Therefore, we investigated the predictive value of physical fitness for survival in older adults with intellectual disabilities.Method: In the Healthy Ageing and Intellectual Disabilities (HA‐ID) study,the physical fitness levels of 900 older adults (≥50 years; 61.5 ± 8.1 years) were measured at baseline. All‐cause mortality was collected over a 5‐year follow‐up period. Cox proportional hazard models were used to determine the association between each physical fitness test and survival, adjusted for age, sex, level of ID, and Down syndrome.Results: The physical fitness components that were independently predictive for survival were manual dexterity (HR = 0.96 [0.94–0.98]), visual reaction time (HR = 1.57 [1.28–1.94]), balance (HR = 0.97 [0.95–0.99]), comfortable gait speed (HR = 0.65 [0.54–0.78]), fast gait speed (HR = 0.81 [0.72–0.91]), grip strength (HR = 0.97 [0.94–0.99]) and cardiorespiratory fitness (HR = 0.997 [0.995–0.999]), with a better physical fitness showing a lower mortality risk.Conclusion: We showed for the first time that physical fitness was independently associated with survival in older adults with intellectual disabilities. Improving and maintaining physical fitness must become an essential part of care and support for this population.