With the accelerating aging of the global population, osteoporosis has emerged as a major public health challenge. As one of the most widely consumed beverages, the relationship between coffee intake and osteoporosis remains controversial. Previous research has often treated coffee as a single entity, neglecting the complexity of its chemical composition. Based on the principle of bone metabolic homeostasis, this review systematically elaborates on the dual regulatory effects of its key constituents—coffee polyphenols and caffeine—on osteoporosis from a compositional perspective. Polyphenols exert protective effects on bone through mechanisms such as antioxidation, anti-inflammation, and modulation of the gut-bone axis, whereas caffeine promotes bone resorption by disrupting calcium homeostasis and potentially activating osteoclasts. By synthesizing the latest evidence and analyzing sources of heterogeneity across studies, this review concludes that the net impact of coffee on bone health is determined by the balance between these components, total daily intake, and individual physiological conditions. This work aims to provide a scientific basis for personalized dietary recommendations regarding coffee consumption for different populations and to inform the development of precise dietary guidance systems.