Bone destruction in rheumatoid arthritis (RA) leads to significant disability, yet effective treatments are limited. Sinomenine (Sino) demonstrates anti-arthritic and bone-protective effects but requires high doses. In this study, we developed a Sino derivative, SINX, and evaluated its efficacy in RA. Safety assessments in mice confirmed its suitability for further study. In vitro, SINX inhibited osteoclast differentiation by reducing TRAP-positive cells, disrupting F-actin ring formation, and suppressing bone resorption pits, alongside downregulating osteoclast-specific genes. It also showed strong anti-inflammatory properties by reducing inflammatory cytokine levels. In vivo, using a collagen-induced arthritis (CIA) mouse model, SINX improved bone integrity by reducing joint inflammation, maintaining trabecular bone density, and preventing erosion. Histological and micro-CT analyses confirmed its effects, including suppressed osteoclast activity and reduced bone resorption-related gene expression. Mechanistically, SINX ameliorated mitochondrial dysfunction, decreased ROS levels, and activated the NRF2/HO-1/NQO1 pathway, enhancing antioxidant defenses. Compared to Sino, SINX achieved similar results at lower doses. These findings highlight the potential of SINX as a safe, effective treatment for RA-related bone destruction.