Given the lack of studies, whether the addition of adjuvant chemotherapy (AC) to concurrent chemoradiotherapy (CCRT) is superior to CCRT alone for locoregionally advanced nasopharyngeal carcinoma (NPC) remains unclear. The main objective of this Bayesian network meta-analysis was to determine the efficacy of CCRT + AC when compared with CCRT alone. We systematically searched databases and extracted data from randomized, controlled trials involving NPC patients randomly assigned to receive CCRT + AC, CCRT, or radiotherapy (RT). Overall survival (OS), locoregional recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) with hazard ratios (HRs) were investigated. A Bayesian network for different outcomes was established to incorporate all evidence. Multiple treatment comparisons based on the network integrated the efficacy of CCRT + AC, CCRT, and RT. Eight studies involving 2144 patients were analyzed. In the network meta-analysis, CCRT + AC and CCRT were both significantly better than RT alone for all outcomes, except that no significant difference was found between CCRT and RT for LRFS. Though ranking probabilities showed that CCRT + AC was ranked superior to CCRT for OS, LRFS, and DMFS, no significant differences were found between CCRT+AC and CCRT for all outcomes OS: HR = 0.86, 95% credible interval (CrI) 0.60–1.16; LRFS: HR = 0.72, 95% CrI 0.43–1.15; DMFS: HR = 0.86, 95% CrI 0.62–1.16. No significant improvement was found following CCRT + AC compared with CCRT alone. Whether the omission of additional AC can reduce toxic effects without adversely affecting survival in patients with locoregionally advanced NPC should be further explored, in addition to the precise patient status that would benefit from AC following CCRT.