Glucocorticoids (GCs) are widely used for their potent anti-inflammatory and immunosuppressive effects, but their use is strongly associated with negative impacts on bone health. Rapid bone loss and an increased risk of fragility fractures are characteristics of glucocorticoid-induced osteoporosis (GIOP), the most common type of secondary osteoporosis. While oral GCs are a well-known cause of GIOP, growing evidence suggests that non-oral routes of administration may also negatively affect the skeleton. This review summarizes current knowledge on the pathophysiology of GIOP, highlighting the complex relationship between direct and indirect mechanisms. It examines the effects of various routes of GC administration—oral, intravenous, inhaled, topical, and epidural—on bone mineral density, microarchitecture, and fracture. While parenteral GCs may have fewer systemic effects than oral therapy, long-term exposure or high cumulative doses may still cause clinically significant skeletal deterioration. This review also discusses current methods for assessing, preventing, and treating the fracture risk associated with GIOP. These strategies include lifestyle modifications, calcium and vitamin D supplements, and medications such as denosumab, bisphosphonates, and anabolic agents. Reducing the incidence of glucocorticoid-associated fractures and improving prevention and treatment requires an understanding of how GCs impact bone.