Background/Objectives: Complete blood count (CBC)-derived markers such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) have gained increasing attention as accessible indicators of systemic inflammation. These parameters, calculated from routine blood tests, are widely available in clinical settings and are potentially relevant for a variety of chronic diseases. This review aims to explore current evidence and highlight potential future directions regarding the use of hematologic inflammatory biomarkers in chronic disease. Methods: We performed an extensive literature search on PubMed to identify full-text original studies published in the past five years, focused on investigating the clinical applications of hematologic inflammatory markers in chronic conditions. Results: CBC-derived inflammatory markers have been studied in a wide range of chronic diseases, including autoimmune diseases, metabolic disorders, chronic kidney disease, chronic infections, psychiatric diseases, and other conditions. These markers have been evaluated for multiple clinical purposes, such as aiding diagnosis, monitoring disease status, assessing disease activity, disease subtype characterization, predicting prognosis, and evaluating associations with disease outcomes. Conclusions: As chronic diseases affect millions of individuals globally, placing a burden for the healthcare system, patients, and their families, simple and cost-efficient tools like CBC-derived inflammatory markers have the potential to improve clinical case management.