Background: Several patient-reported outcome measures (PROMs) are available for assessing the outcomes following ankle fractures. This study aimed to evaluate validity, reliability, and responsiveness and detect the minimal clinically important difference of the Foot and Ankle Outcome Score (FAOS) in patients with ankle fractures. Methods: The study design is a prospective cohort study, including all patients treated both conservatively and surgically following an ankle fracture (AO-43A/B/C). Content validity, test-retest reliability, responsiveness, and minimal clinically important difference were evaluated from 14 days to 3 months following the fracture. Results: The study population consisted of 52 females and 24 males. The mean age was 52.0 years (range, 15-75 years). The percentage of patients at 12 weeks reporting the 5 subscales at least somewhat relevant were pain, 77%; symptoms, 75%; activities of daily living (ADL), 64%; sport, 81%; and quality of life (QOL), 88%. High test-retest reliability of the FAOS questionnaire was observed. The interclass coefficients were 0.78, 0.77, 0.71, 0.73, and 0.74 for the pain, symptoms, ADL, sport, and QOL subscales, respectively. Responsiveness was evaluated with high effect size for the symptoms (0.83), ADL (1.19), sport (4.36), and QOL (2.12) subscales. The minimal clinically important difference of the FAOS was 14 (95% CI, 12-17). Conclusion: The FAOS during early recovery after ankle fracture has high reliability and validity. Level of Evidence: Level II, prospective cohort study