Lung metastasis is a major cause of mortality in patients with osteosarcoma (OS). A better understanding of the molecular mechanism of OS lung metastasis may facilitate development of new therapeutic strategies to prevent the metastasis. We have established high‐ and low‐metastatic sublines (LM8‐H and LM8‐L, respectively) from Dunn OS cell line LM8 by using in vivo image‐guided screening. Among the genes whose expression was significantly increased in LM8‐H compared to LM8‐L, the transcription factor lymphoid enhancer‐binding factor 1 (LEF1) was identified as a factor that promotes LM8‐H cell extravasation into the lungs. To identify downstream effectors of LEF1 that are involved in OS lung metastasis, 13 genes were selected based on LM8 microarray data and genomewide meta‐analysis of a public database for OS patients. Among them, the cytoglobin (Cygb) gene was identified as a key effector in promoting OS extravasation into the lungs. CYGB overexpression increased the extravasation ability of LM8‐L cells, whereas knocking out the Cygb gene in LM8‐H cells reduced this ability. Our results showed a novel LEF1‐CYGB axis in OS lung metastasis and may provide a new way of developing therapeutic strategies to prevent OS lung metastasis. We found that the cytoglobin (Cygb) gene is an important effector that promotes extravasation of osteosarcoma (OS) to the lungs. Our data showed a novel function of the LEF1‐CYGB axis in OS lung metastasis and may provide novel targets for drugs that prevent OS lung metastasis.