Introduction: Facioscapulohumeral muscular dystrophy (FSHD) is one of the most prevalent muscular dystrophies. Nevertheless, little is known about the risk of developing functional impairment. Here we determine the 6‐year risk of functional impairment in FSHD. Methods: A retrospective cohort of 313 genetically confirmed, clinically affected FSHD participants in a United States registry between January 2002 and June 2011. Our main outcome was wheelchair (WC) use. Results: The 6‐year risk of WC use was 24.0% (95% confidence interval 18.6–29.3). The distribution of WC risk was bimodal, with a peak in the second decade associated with large D4Z4 contractions, followed by an age‐related increase in risk. Other functional categories showed moderate risk. Prevalence of hearing aid use and difficulty pronouncing words was increased in large D4Z4 contractions. Conclusions: The 6‐year risk of functional impairment in FSHD is moderate, and early WC use is associated with large D4Z4 contractions. Muscle Nerve 49:520–527, 2014