This study aimed to map systemic alterations predisposing to oral squamous cell carcinoma (OSCC) onset. This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses. Five databases were used to access (1) reports of OSCC co‐occurring in patients with systemic conditions, (2) prevalence of OSCC among these patients, and (3) clinicopathological profiles. Data from more than 1 million patients worldwide showed that Fanconi's anemia, xeroderma pigmentosum, dyskeratosis congenital, chronic fatigue syndrome, and patients post bone marrow transplantation (BMT) present increased risk for OSCC development. The overall prevalence of OSCC in syndromic patients and post‐BMT were 0.65% (95% CI = 0.13–3.11, p < 0.01) and 5.83% (95% CI = 0.00–30.90, p < 0.01), respectively. The certainty of the evidence was moderate. This study demonstrated that some systemic conditions predispose to OSCC. These results present an impact on the screening of OSCC in systemically compromised patients.