Osteoporosis is a progressive systemic skeletal disorder characterized by reduced bone mineral density and deterioration of bone microarchitecture, representing one of the foremost public health challenges of the twenty-first century. With an estimated 200 million individuals affected worldwide and a substantial burden of fragility fractures associated with significant morbidity, mortality, and healthcare expenditure, the need for effective, safe, and sustainable therapeutic strategies remains acute. Current pharmacological options, including bisphosphonates, selective estrogen receptor modulators, and parathyroid hormone analogues, are associated with adverse effects such as osteonecrosis of the jaw, atypical femoral fractures, cardiovascular risks, and poor long-term tolerability, thereby limiting their widespread and prolonged use. This review comprehensively examines the evidence pertaining to plant-derived compounds, including flavonoids, phytoestrogens, polyphenols, and terpenoids, as adjunctive or alternative agents in the prevention and management of osteoporosis. Mechanistically, these phytochemicals exert their osteogenic effects through stimulation of osteoblast proliferation and differentiation, inhibition of osteoclastogenesis via modulation of the RANKL/RANK/OPG axis, reduction of oxidative stress, and hormonal modulation through estrogen receptor pathways. Preclinical evidence from in vitro and animal studies demonstrates considerable promise, while clinical trials provide preliminary validation of efficacy and safety. Despite encouraging findings, significant challenges remain in the areas of bioavailability, standardization of plant extracts, and translation from bench to bedside. This review synthesizes current knowledge, critically evaluates translational challenges, and highlights future directions for the integration of plant-derived compounds into mainstream osteoporosis therapeutics.