Histone lysine demethylase 4A (KDM4A) plays a crucial role in regulating cell proliferation, cell differentiation, development and tumorigenesis. However, little is known about the function of KDM4A in muscle development and regeneration. Here, we found that the conditional ablation of KDM4A in skeletal muscle caused impairment of embryonic and postnatal muscle formation. The loss of KDM4A in satellite cells led to defective muscle regeneration and blocked the proliferation and differentiation of satellite cells. Myogenic differentiation and myotube formation in KDM4A-deficient myoblasts were inhibited. Chromatin immunoprecipitation assay revealed that KDM4A promoted myogenesis by removing the histone methylation mark H3K9me3 at MyoD, MyoG and Myf5 locus. Furthermore, inactivation of KDM4A in myoblasts suppressed myoblast differentiation and accelerated H3K9me3 level. Knockdown of KDM4A in vitro reduced myoblast proliferation through enhancing the expression of the cyclin-dependent kinase inhibitor P21 and decreasing the expression of cell cycle regulator Cyclin D1. Together, our findings identify KDM4A as an important regulator for skeletal muscle development and regeneration, orchestrating myogenic cell proliferation and differentiation.