Bone homeostasis is a relative balance between bone formation and resorption. Signal transducer and activator of transcription 3 (STAT3), which is closely related to bone homeostasis, takes part in multiple intracellular and extracellular signal pathways. STAT3 participates in the process of osteoblast differentiation regulated by several factors. It also plays a role in the maintenance of bone homeostasis by regulating the recruitment, differentiation and activation of osteoclasts. In addition, STAT3 is involved in the interaction between osteoblasts and osteoclasts. Patients with STAT3 mutations can have several inherited bone metabolism diseases. Furthermore, STAT3 has a critical role in load-driven bone remodeling. Mechanical stimulation promotes osteoblast differentiation and bone formation through activating or enhancing STAT3 expression during bone remodeling process. Our review summarizes the participation of STAT3 in maintaining bone homeostasis together with its possible mechanisms and discusses the connection between STAT3 and mechanical stimulation in bone remodeling. It may provide a potential pharmacological target for the treatment of bone diseases.