Introduction: To determine predictors of hepatic steatosis by the computed attenuation parameter (CAP) and fibrosis via transient elastography (TE) in persons on methotrexate (MTX) therapy with rheumatologic and dermatologic diseases. Methods: A single-centred retrospective cohort study was performed. Patients on >6 months of MTX for a rheumatologic or dermatologic disease who had undergone TE from January 2015 to September 2019 were included. Multivariate analysis was performed to determine predictors of steatosis and fibrosis. Results: A total of 172 patients on methotrexate were included. Psoriasis was the most frequent diagnosis ( n = 55), followed by rheumatoid arthritis ( n = 45) and psoriatic arthritis ( n = 34). Steatosis (CAP ≥245 dB/m) was present in 69.8% of patients. Multivariate regression analysis revealed that diabetes mellitus (OR 10.47, 95% CI 1.42–75.35), hypertension (OR 5.15, 95% CI 1.75–15.38), and BMI ≥30 kg/m2 (OR 16.47, 95% CI 5.56–45.56) were predictors of steatosis (CAP ≥245 dB/m). Predictors of moderate to severe fibrosis (Metavir ≥F2 = TE ≥8.0kPa) by multivariate regression analysis included moderate to severe steatosis (CAP ≥270 dB/m) (OR 8.36, 95% CI 1.88–37.14), diabetes mellitus (OR 2.85, 95% CI 1.09–7.48), hypertension (OR 5.4, 95% CI 2.23–13.00), dyslipidemia (OR 3.71, 95% CI 1.50–9.18), and moderate alcohol use (OR 3.06, 95% CI 1.2–7.49). Conclusions: In patients on MTX for rheumatologic and dermatologic diseases, hepatic steatosis as measured by CAP was common and moderate to severe steatosis predicted moderate to severe fibrosis.