Objective: This single-center, single-blind, randomized, prospective controlled clinical trial aimed to investigate comprehensively the therapeutic efficacy of electroacupuncture (EA) adjunct to nonsurgical periodontal therapy (NSPT) on the effect of inflammation on the periodontal structures of patients with Stage 3-Grade B periodontitis. Method: Fifty-two participants, of whom 26 underwent full-mouth scaling and root planning (fmSRP) alone, and 26 underwent EA (baseline [T0], fourth day [T1], and seventh day [T2]) in addition to fmSRP. The contribution of EA was evaluated both clinically and biochemically. The clinical periodontal parameters were recorded at T0 and three weeks later (T3). Saliva and serum samples were obtained at T0, T2, and T3. Interleukin 6 (IL-6), IL-10, and tumor necrosis factor-alpha (TNF-α) levels in the saliva and serum were evaluated using ELISA. Results: All clinical periodontal parameters were significantly improved in both groups at 3 weeks later compared to baseline (p < 0.001). Moreover, EA led to a significantly greater decrease in gingival indices (p < 0.001). IL-6 and TNF-α levels decreased significantly within each group over sessions (T0, T2, T3) (p < 0.001). In contrast, IL-10 levels increased significantly within each group over sessions (T0, T2, T3) (p < 0.001) in both groups. Serum IL-6 (T3) and levels and saliva IL-6 (T2 and T3) and levels were significantly lower in AG (p < 0.001). Serum and saliva IL-10 (T2 and T3) levels were significantly higher in AG (p < 0.001). Conclusions: This study indicates that the administration of EA when combined with NSPT may have a noticeable effect on the treatment of periodontitis, which is by influencing changes in clinical and biochemical parameters.