Periodontitis is a chronic inflammatory disease driven by microbial dysbiosis and an exacerbated host immune response, leading to progressive periodontal tissue breakdown and contributing to systemic inflammation. Although scaling and root planing remains the standard treatment, its capacity to fully restore immune balance and host–microbiota homeostasis is limited. In this context, probiotics have emerged as promising adjunctive strategies capable of modulating immunological and metabolic pathways involved in disease progression. This narrative review aimed to evaluate current evidence regarding the use of probiotics in periodontal therapy. The review followed the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines. A literature search was conducted in MEDLINE via PubMed for manuscripts indexed up to January 2026 using MeSH-based terms related to periodontitis and probiotics. Evidence from preclinical and clinical studies suggests that probiotics may reduce alveolar bone loss and periodontal inflammation by downregulating proinflammatory mediators, enhancing anti-inflammatory cytokine production, strengthening epithelial barrier function, and modulating innate and adaptive immune responses. Additionally, probiotics may exert systemic effects through interactions with the gut microbiota, potentially improving metabolic regulation and reducing systemic inflammation. Overall, current evidence supports probiotics as biologically plausible adjuncts to periodontal therapy.