Miichthys miiuy is one of the main economic fish species in the offshore waters of Zhejiang Province. In order to investigate the spatio-temporal distribution of this local fish stock, this study developed suitability curves of M. miiuy to environmental factors, using relative abundance and associated environmental data from the bottom trawl fishery surveys during 2022 to 2023 in the offshore waters of Zhejiang. Subsequently, boosted regression trees (BRT) was applied to estimate the weight of each environmental factor, and two composite habitat suitability index (HSI) models were established using the arithmetic mean method (AMM) and the geometric mean method (GMM), separately. The accuracy of HSI models was evaluated using the Akaike information criterion (AIC). The results revealed distinct seasonal patterns in the optimal habitats of M. miiuy in offshore Zhejiang. In spring, optimal habitats were primarily located in the Zhoushan fishing grounds and the waters surrounding the Dongtou Islands, characterized by bottom salinity of 28.0‒32.1, temperature of 14.2‒16.3 ℃, dissolved oxygen of 7.8‒9.5 mg/L, and water depth of 16‒41 m. During summer, optimal habitats shifted to coastal estuary waters, with optimal ranges of 26.4‒31.5 for bottom salinity, 24.8‒28.1 ℃ for temperature, 6.9‒8.7 mg/L for dissolved oxygen, and 14‒35 m for depth. In autumn, optimal habitats moved further offshore, with preferred conditions of 28.4‒33.1 for bottom salinity, 19.2‒24.2 ℃ for temperature, 5.8‒8.4 mg/L for dissolved oxygen, and 21‒44 m for depth. Winter habitats were concentrated between 123°E and 124°E, with optimal ranges of 30.0‒34.1 for bottom salinity, 11.0‒14.1 ℃ for temperature, 8.3‒9.6 mg/L for dissolved oxygen, and 43‒60 m for depth. The BRT identified bottom salinity as the most influential factor in spring and summer, while depth and bottom temperature dominated in autumn and winter. Based on AIC evaluation, the GMM-weighted HSI model exhibited higher accuracy in autumn, whereas the AMM-weighted HSI model performed better in spring, summer, and winter. These results highlight significant seasonal variations in the spatio-temporal distribution of M. miiuy habitat, which might be driven by dynamic environmental factors and the distinguish habits of this species.