The AlkB homolog 7 (ALKBH7) is a nonheme iron (II) α-ketoglutarate-dependent dioxygenase superfamily member, which may affect the progression of several types of human cancer. However, the biological effect, especially the immune-related effect, of ALKBH7 in HNSC remains unclear. Herein, several databases were employed at first to assess the different expression of ALKBH7 as well as their relationship to the prognosis, RNA modification, DNA methylation modulation, immune microenvironment and chemotherapeutic responses of various types of cancers. We found that ALKBH7 was expressed differentially in pan-cancer, and correlated with a satisfied prognosis especially in HNSC. The expression of ALKBH7 was also associated with the level of immune cell infiltration, TMB, MSI, HRD, MMR deficiency, and DNA methyltransferases in a wide variety of cancers, which might be potentially related to the responses against chemotherapeutic agents. Next, the role of ALKBH7 in HNSC was further investigated. Western blot and immunohistochemical analysis in HNSC patients from the NMU cohort showed the reduced ALKBH7 expression level in tumor tissues. In vitro experiments of cell migration, invasion, and proliferation showed a potential protective effect of ALKBH7 in HNSC. Collectively, ALKBH7 might play a protective role in the development and progression of multiple cancers by affecting the metabolism and immune cell infiltration, especially HNSC, which could be a potential biomarker to predict prognosis and chemotherapeutic response.