The study investigated the relationship between inflammatory markers and osteoporosis in older adults in China. The study included 3,625 participants aged 60 and over who were followed up at four hospitals from January 2023 to May 2025. The results showed that increased levels of inflammatory indices were associated with a higher likelihood of osteoporosis, while the relationship between inflammation and osteoporosis was non-linear. Among all indices examined, the summary index of systemic inflammation (AISI) was shown to be the strongest predictor of osteoporosis with an OR = 1.63 (95% CI: 1.49–1.78). These findings were consistent in further analyzes and different patient groups. The study concluded that AISI represents a new, cost-effective tool for the early identification of osteoporosis in clinical practice.