Background: Sjögren’s syndrome (SS) is a systemic autoimmune disorder characterized by lymphocytic infiltration of exocrine glands, leading to dryness of the mouth and eyes. When SS occurs in association with rheumatoid arthritis (RA), it is known as secondary Sjögren’s syndrome (sSS). The coexistence of these two diseases significantly impacts disease progression, and patient quality of life. Aim: This review aims to summarize and analyze recent literature concerning the prevalence and severity of SS among RA patients across different populations, with special attention to variations in diagnostic criteria, immunological markers, and therapeutic implications. Methodology: A structured literature search was conducted in PubMed, Scopus, and Google Scholar databases, focusing on studies published between 2018 and 2025. The review includes data from multiple cohort, cross-sectional, and population-based studies that met the 2010 ACR/EULAR classification criteria for RA and the 2016 ACR/EULAR criteria for SS. Results: Findings consistently demonstrate that the prevalence of SS among RA patients ranges between 8% and 22% in Western populations and up to 40% in Asian populations, suggesting both genetic and diagnostic influences. RA-SS patients exhibit distinct serological profiles, including elevated anti-Ro/SSA and anti-La/SSB antibodies, and are more prone to ocular surface disorders, fatigue, and systemic complications. Conclusion: Despite variations among studies, the evidence supports that SS represents a frequent and clinically relevant comorbidity in RA. Standardized diagnostic methods and unified criteria are essential for accurate prevalence estimation and better clinical management. Future large-scale, prospective studies are needed to clarify the immunopathogenic links between these two autoimmune diseases.