Bone is a common site of metastasis in lung cancer, but the regulatory mechanism remains incompletely understood. Osteoclasts are known to play crucial roles in osteolytic bone metastasis by digesting bone matrix and indirectly enhancing tumor colonization. In this study, we found that IL receptor 20 subunit beta (IL-20RB) mediated a direct tumoral response to osteoclasts. Tumoral expression of IL-20RB was associated with bone metastasis of lung cancer, and functionally, IL- 20RB promoted metastatic growth of lung cancer cells in bone. Mechanistically, tumor cells induced osteoclasts to secrete the IL20RB ligand IL-19, and IL-19 stimulated IL-20RB-expressing tumor cells to activate downstream JAK1/STAT3 signaling, leading to enhanced proliferation of tumor cells in bone. Importantly, blocking IL-20RB with a neutralizing antibody significantly suppressed bone metastasis of lung cancer. Overall, our data revealed a direct protumor role of osteoclastic niche in bone metastasis and supported IL-20RB-targeting approaches for metastasis treatment.