Improvements in treatment and chemotherapy have increased the survival rate of osteosarcoma, but overall efficacy remains low, highlighting the need for new gene therapy methods. Clustered regularly interspaced short palindromic repeats–deactivated Cas9 (CRISPR–dCas9) technology offers a promising strategy, but targeting osteosarcoma cells precisely is a challenge. We designed a system to achieve specific expression of CRISPR–dCas9–KRAB in osteosarcoma cells by using the creatine kinase muscle (CKM) promoter to drive dCas9–KRAB and the telomerase reverse transcriptase (TERT) promoter to drive single guide (sg)RNA expression. We inhibited theMDM2proto-oncogene using this system in vitro, which efficiently inhibited the malignant behavior of osteosarcoma cells and induced apoptosis without affecting normal cells. In vivo experiments demonstrated that this system effectively inhibited the growth of subcutaneously transplanted tumors in nude mice. These findings provide a new method for precise identification and intervention of osteosarcoma with significant implications for the development of gene therapy methods for other cancers. Future research should focus on optimizing this system for clinical translation.