This review synthesizes the role of Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (A.a) in modulating immune responses through citrullination and assesses its impact on periodontitis and systemic conditions. A systematic review was conducted on preclinical and clinical studies focusing on Pg- and A.a-induced citrullination and its effects on immune responses, particularly inflammatory pathways and on systemic diseases. The search included PubMed, Scopus, Google Scholar, Web of Science, and gray literature. Quality and risk of bias were assessed using OHAT Rob Toll and QUIN-Tool. The review is registered in PROSPERO (ID: CRD42024579352). 18 articles published up to August 2024 were included. Findings show that Pg and A.a citrullination modulates immune responses, leading to neutrophil dysfunction and chronic inflammation. Key mechanisms include citrullination of antimicrobial peptides, CXCL10, histone H3, α-enolase, and C5a, impairing neutrophil activation and promoting NET formation. This review suggests that Pg and A.a citrullination modulates immune responses and may influence periodontitis and systemic conditions like RA. Beyond ACPA production, these pathogens affect key proteins such as H3, C5a, and CXCL10, as well as antimicrobial peptides, NET formation, and phagocytosis. These interactions lead to neutrophil dysfunction and potentially affect other cells, subsequently disrupting local and systemic inflammatory responses.