Objective To explore the correlation between thyroid hormone (TH) sensitivity and metabolic dysfunction-associated steatotic liver disease (MASLD) in euthyroid patients. Methods The euthyroid patients hospitalized in the Department of Endocrinology at Zhongshan Hospital, Fudan University, from January 2016 to December 2020 were enrolled. All patients were evaluated for free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH). The FT3/FT4 ratio, thyroid-stimulating hormone index (TSHI), FT3 feedback quantile index (TFQIFT3), and FT4 feedback quantile index (TFIQFT4) were calculated. Hepatic controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) were assessed by FibroScan. Results A total of 4 869 participants were enrolled, 3 485 (71.58%) were diagnosed with MASLD. Compared with non-MASLD group of patients, MASLD group had significantly higher levels of serum FT3 and thyroid sensitivity-related parameters, including FT3/FT4, TSHI, TFQIFT3, and TFIQFT4 (P＜0.05). After multivariate adjustment for potential confounders, serum FT3, FT3/FT4, TFQIFT4, TFQIFT3, and TSHI remained positively correlated with the risk of MASLD (P＜0.05). Further analysis revealed that, after adjustment for confounders, FT3, FT3/FT4, TFQIFT4, TFQIFT3, and TSHI were positively correlated with CAP, and TFQIFT4, TFQIFT3, and TSHI were also positively correlated with LSM (P＜0.05). Conclusions Reduced thyroid hormone sensitivity are independently associated with MASLD. Moreover, higher levels of FT3 and decreased thyroid hormone sensitivity are correlated with the progression of MASLD.