Chinese dwarf cherry (Cerasus humilis) is a fruit unique to China, which is considered to have osteoprotective effects. However, no systematic experimental characterization was available. In this study, the osteoprotective activity and mechanism of Chinese dwarf cherry polyphenol extract (OPE) was studied. In vitro, OPE stimulated the alkaline phosphatase activity in the early differentiation stage, increased the osteocalcin level in the middle differentiation stage, and induced the formation of more bonemineralized nodules in the late osteogenic stage. In vivo, OPE improved cancellous bone structure and maximum load of the femur in ovariectomized (OVX) rats. The balance between bone formation and resorption was regulated. Oxidative stress levels in the peripheral blood, liver and femur were reduced. OPE alleviated the disturbance in energy metabolism, muscle development, and muscle regulation-related signaling pathways caused by OVX and activated the calcium/adenosine monophosphate-activated protein kinase signaling pathway. Therefore, OPE is a potential dietary supplement for the prevention and treatment of osteoporosis.