Osteosarcoma is the most common type of primary malignant bone tumor and has a high propensity to metastasize to the lungs and bones. Calbindin 1 (CALB1) is a constituent Ca2+ binding protein, which can prevent apoptotic death in several cell types induced through various pro‑apoptotic signaling pathways. To investigate whether CALB1 is implicated in the tumor growth of human osteosarcoma, two different short hairpin RNAs (shRNAs) against CALB1 were used for CALB1-knockdown in osteosarcoma U2OS cells. The U2OS cells were divided into three groups: Two groups with CALB1 knockdown (CALB1-shRNA 1 and CALB1‑shRNA 2) and one control group (Con‑shRNA). Reverse transcription‑quantitative polymerase chain reaction and western blot analysis confirmed that the CALB1‑shRNA 1‑and 2‑infected cells exhibited significantly lower levels of CALB1 gene and protein expression compared with the Con‑shRNA group. The proliferation and colony formation abilities were significantly inhibited in CALB1‑deficient U2OS cells compared with the control, as measured using an MTT assay and crystal violet staining. Flow cytometry revealed that the number of CALB1‑shRNA 2‑injected cells was increased in the G0/G1 and G2/M phases, but decreased in the S phase, compared with the control group. The assessment of apoptosis and necrosis using Annexin V/7‑aminoactinomycin D demonstrated that there was a significantly higher percentage of necrotic, early apoptotic, and late apoptotic cells, but a significantly lower percentage of viable cells in U2OS cells with CALB1‑knockdown compared with the control group. In conclusion, CALB1 contributes to protecting osteosarcoma cells from apoptosis and provides a potential novel target for gene therapy to treat patients with osteosarcoma.