BACKGROUND: Even in the early stages, cognitive impairment (CI) is commonly seen in multiple sclerosis (MS) patients. The current study set out to estimate the frequency and contributing factors for developing CI among a large group of drug-naïve MS patients. METHODS: 42 healthy controls matched for age, sex, and education were included in the study, along with 140 drug-naïve MS patients who were diagnosed using the 2017 McDonald criteria for MS. Patient data included complete clinical and demographic information and clinical scales including, Expanded Disability Status Scale (EDSS), 9-Hole Peg test (9-HPT), Brief International Cognitive Assessment Scale of MS (BICAMS) and serum level light chain (sNFL) were assessed at the initial visit following diagnosis. RESULTS: Among MS patients who had never taken medication, CI was noticeably high (27.14 %). In comparison to other clinical phenotypes among drug-naïve MS patients, the SPMS had the highest incidence of CI (55.56 %) and the lowest among CIS (11.76 %). First motor presentation and low years of education were significantly linked to CI (0.026, and 0.008 respectively). Patients with CI had significantly higher EDSS (P = 0.012) and 9-HPT scores (P = 0.006) compared with non-CI patients. Additionally, sNFL was significantly higher in CI than non-CI group (P = 0.026). 9-HPT and motor presentation at onset were the only independent contributing factors of CI in multivariate regression analysis with CI. CONCLUSION: The current study demonstrates that a significant portion of MS patients who are drug-naïve have CI. Motor symptoms at onset and 9-HPT performance were identified as independent contributing factors of CI. Elevated serum NFL levels reflect associated neuroaxonal damage rather than being a direct contribution. TRIAL REGISTRATION: Clinicaltrial.gov registry number NCT06197841.