Runt-related transcription factor-2 (RUNX2) is an integral player in osteogenesis and is highly expressed in osteosarcoma. Emerging evidence suggests that aberrant RUNX2 expression is a key factor in osteosarcoma oncogenesis. Patients with advanced stages of osteosarcoma overexpressing RUNX2 are more likely to have high tumour grades, metastasis, and lower overall or progression-free survival rates. Thus, RUNX2 is considered a potential candidate for targeted therapy of osteosarcoma. Hypoxia-inducible factor-1α (HIF-1α) is a key transcription factor involved in the regulation of cellular reprogramming in response to hypoxia. Overexpression of HIF-1α decreases overall survival, disease-free survival, and chemotherapy response and promotes tumour stage and metastasis. Hence, our review focused on highlighting the intricate network between RUNX2 and HIF-1α, which support each other or may work synergistically to develop resistance to therapy and osteosarcoma progression. An in-depth understanding of these two important tumour progression markers is required. Therefore, this review focuses on the role of RUNX2 and HIF-1α in the alteration of the tumour microenvironment, which further promotes angiogenesis, metastasis, and resistance to therapy in osteosarcoma.