Objective To investigate the mechanism of pyroptosis production in colorectal cancer cells by Newcastle disease virus (NDV) via natural killer (NK) cell activation through granzyme A (GZMA) secretion, with specific focus on the role of gasdermin B (GSDMB) expression level in this process. Methods NK cells were co-cultured with NDV at different concentrations [NDV1, 2, 3: 0.001, 0.010, 0.100 hemagglutinin/mL] for 16 h, and blank control (culture medium only) as well as non-stimulated NK cell control were set. All groups were subsequently incubated with high (SW837) or low (SW480) GSDMB expression colorectal cancer cells. Quantitative PCR and ELISA were used to detect the gene expression and protein secretion levels, respectively, of effector molecules in NK cells. Cell proliferation, cytotoxicity and lactate dehydrogenase (LDH) release were measured to assess the cell viability and pyroptosis in 2 tumor cell lines. Cell morphology observation and Western blot of GSDMB cleavage were applied to verify NK cell-mediated pyroptosis effect. Results Quantitative PCR and ELISA results indicated that NDV stimulation upregulated the gene expression and protein secretion levels of GZMA, IFN-γ, and perforin in NK cells. The highest protein secretion levels of GZMA (t = 6.70, P = 0.003) and IFN-γ (t = 13.66, P < 0.001) were reached in NDV3 stimulation, and were statistically significantly higher than non-stimulated NK control. Comparing with non-stimulated NK cell control treated, cell viability inhibition [NDV3-NK at effector-to-target ratio (E/T) =1, 2: t = -10.17, -25.94, both P < 0.001], LDH release (NDV3-NK at E/T=1, 2: t = 13.70, 9.75, both P < 0.001), and N-terminal GSDMB (NDV2-NK at E/T=1, 2: t = 6.80, 3.07, both P < 0.05) of with stimulated NK cell treated SW837 all increased statistically significantly. Pyroptosis-related features such as plasma membrane blebbing and swelling were observed in SW837, but not in SW480 cells, even though viability inhibition and cell damage were seen in SW480. Conclusion NDV-activated NK cells induce pyroptosis in colorectal cancer cells via GZMA secretion, particularly in cells with high GSDMB expression.