Inflammatory responses play an important role in cancer survival and progression. For this reason, cancer can be treated by targeting inflammatory responses. It has been known that plasma treatment has an anti-inflammatory and anticancer effect. However, the mechanism by which N2/Ar plasma (NTP) induces cancer cell death and inhibits inflammation is unknown. In this study, we determined how NTP suppresses the progression of head and neck cancer (HNC). We found that the levels of inflammation-related and mitochondrial antiviral signaling (MAVS) proteins were elevated in HNC patient samples and that treatment of HNC cells with N2/Ar plasma decreased the expression of MAVS. In addition, N2/Ar plasma treatment inhibited the inflammatory response and induced necroptosis. We also identified that among the components of N2/Ar plasma-treated solution, peroxynitrite is mainly involved in the induction of necroptosis and upregulation of the expression of phosphorylated mixed lineage kinase domain-like protein. These results suggest that N2/Ar plasma might be used to treat HNC through the induction of necroptosis and inhibition of inflammatory responses.