In this work, MoS2 nanosheets with diverse morphologies and their nanocomposites with PEDOT:PSS are synthesized at relatively low temperature via a hydrothermal process using ammonium heptamolybdate tetrahydrate (AHT), thiourea (Th), and citric acid as precursors. The study investigates the effects of varying concentrations of AHT and Th in acidic condition on the growth, morphology, and optical properties of MoS2 nanosheets and their nanocomposites with PEDOT:PSS. Morphology, chemical composition, and optical properties of the MoS2/PEDOT:PSS nanocomposites are studied using Field Emission Scanning Electron Microscopy(FESEM), FTIR, UV–Vis, and photoluminescence spectroscopy. The FESEM images indicate that the MoS2 nanosheets exhibited large, uniform rectangular and leaf-like structures formed through the stacking of multiple nanosheets. Moreover, the concentration of the PEDOT:PSS polymer is found to have a significant impact on the morphological and optical properties of the MoS2/PEDOT:PSS nanocomposites. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.