In this work, ZnO, WO₃, and MgO were doped into InSnZnO (ITZO) films via co-sputtering to enhance the mobility and stability of ITO-based thin film transistors (TFTs). ITZO, InSnWO (ITWO) and InSnMgO (ITMO) films were fabricated, and the effect of cation dopants on the oxygen stoichiometry in ITO films was investigated. We further discussed their influence on the electrical parameters of corresponding TFTs, including threshold voltage ($V_{\mathrm{th}}$), subthreshold swing (SS), and field-effect mobility (${\mu }_{\mathrm{FE}}$). Additionally, the positive and negative bias stress stability of these devices was evaluated. The results demonstrate that ITWO TFTs exhibit superior stability despite a reduction in mobility. This is attributed to the high electronegativity of W⁶⁺ and the strong W-O bonding, which effectively mitigate the formation of oxygen vacancies and suppress the adsorption of impurities at the back channel. The findings provide valuable insights for the material design of high-performance TFTs.