Becker’s muscular dystrophy (BMD) is a milder, yet clinically heterogeneous, dystrophinopathy compared to Duchenne muscular dystrophy (DMD). It arises from in-frame mutations in the dystrophin gene, producing truncated but partially functional dystrophins, resulting in highly variable disease severity that can range from severe impairment to asymptomatic cases. In this study, we performed urinary proteome profiling to identify potential non-invasive protein biomarkers for assessing muscle injury in individuals with BMD, encompassing a broad spectrum of disease severities and ages.