This systematic review and meta-analysis assessed the impact of probiotic supplementation on treating chronic periodontal (CP) disease based on clinical and microbiological findings. Four databases were searched: Medline, Embase, Cochrane Library, and the Web of Science databases. The references to relevant studies were also manually searched. Analyses were conducted using the Review Manager 5.2 software, while the quality of randomised controlled trials was assessed with the Cochrane Risk of Bias tool. In total, 19 studies were included in the meta-analysis. Pooled results revealed that the adjuvant use of probiotics in the treatment of patients with periodontal disease was largely associated with good clinical efficacy. Resulting in statistically significant improvements in plaque index (P<0.05), periodontal probing depth (P<0.05), clinical attachment level (P<0.05), gingival index (P<0.05), bleeding on probing (P<0.05), deep probing depth (P<0.05), and levels of subgingival microbes (P<0.05) following probiotic supplementation. In summary, the results of this meta-analysis suggest that the administration of probiotics together with scaling and root planing can somewhat improve CP patient clinical outcomes and reduce levels of periodontal pathogens. However, more comprehensive experiments are needed to standardise probiotics and maximise their adjuvant therapy.