We demonstrate solution processed oxide semiconductor thin-film transistors (TFTs) with high performance as well as improved electrical/thermal temperature stress stabilities. Yttrium-doped ZnO (YZO) TFTs are fabricated using aqueous precursors prepared via direct dissolution of metal hydroxides. The Y contents in YZO films are critical for determining the intrinsic electrical properties as well as the positive bias stress-, negative bias stress-, and negative bias temperature stress-induced instabilities. Solution processed 1% Y-doped ZnO TFT annealed at 350 °C exhibits a noticeably lower threshold voltage shift of 3.78 V under positive bias stress and −1.72 V under negative bias temperature stress as well as the good device performance with a mobility of ∼1.8 cm² V⁻¹ s⁻¹ and an on/off current ratio of ∼10⁷. Our results suggest that solution processed Y-doped ZnO TFTs have potential for use in high stability performance applications in transparent devices.