Aims: The present study aimed to detect the expression of tetraspanin 8 (TSPAN8) in human nasopharyngeal carcinoma (NPC) tissues, and to investigate the role of TSPAN8 in NPC radioresistance and related molecular mechanism. Methods: A total of 35 fresh human NPC tissues and the adjacent normal tissues were collected, and a radioresistant cell line CNE-2R was established. TSPAN8-pcDNA3.1 was constructed into the CNE-2 cells to overexpress TSPAN8, and LY294002 was used to suppress phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) signaling pathway in CNE-2 cells. Expression of TSPAN8 and phosphorylated AKT was detected using RT-qPCR and/ or western blot analysis. MTT, colony formation and flow cytometry analyses were used to determine cell growth, survival fraction (SF) and cell apoptosis. Results: TSPAN8 was upregulated in human NPC tissues and the radioresistant cells CNE-2R. Overexpression of TSAPN8 led to enhanced radioresistance of CNE-2 cells, by promoting cell growth and SF, as well as inhibiting cell apoptosis. Further, we found TSPAN8 positively regulated the phosphorylation of AKT so as to activate the AKT signaling. However, TSPAN8 induced-radioresistance in NPC was reversed by PI3K/AKT signaling suppression. Conclusion: This study firstly demonstrated TSPAN8 expression was elevated in human NPC tissues and radioresistant NPC cell line CNE-2R, and TSPAN8 could promote NPC radioresistance at least partially via the activation of PI3K/AKT signaling pathway. These findings may help in sensitization of NPC to radiotherapy.