Background: Impaired physical function after intensive care unit (ICU) stay is common. We aimed to study the association between activity levels in the ward after discharge from ICU and physical function at 3-month follow-up. Methods: Prospective cohort study of adult patients admitted to the ICU for more than 24 hours. Patients wore an accelerometer for up to 7 days at the ward. At discharge from ICU and at 3-month follow-up, patients were tested with the Chelsea Critical Care Physical Assessment Tool (CPAx). Results: We screened 66 consecutive, eligible patients; 41 completed actigraphy and 19 patients were visited at 3 months. The median CPAx increased from 31 (IQR 23-41) at discharge from ICU to 47 (IQR 44-49) at follow-up (P < 0.0001). Mean daily activity for the first week was correlated with CPAx at ICU discharge (R ²  = 0.14, P = 0.017; all 41 patients). For the 19 visited patients, we found no significant correlation for activity levels with CPAx at ICU discharge (R ²  = 0.12, P = 0.14) nor at visit (R ²  = 0.2, P = 0.058). Conclusion: We found improved physical function for most patients 3 months after ICU treatment. Activity levels for 1 week after ICU discharge at the ward were not associated with better physical function at 3-month follow-up.