Solution-processed amorphous metal oxide semiconductors (AOSs) are promising candidates for printed electronics. However, process durability and bias stress instability issues still hinder their practical applications. Here, a poly(methyl methacrylate)/parylene/AlOx hybrid passivation approach was developed for AOS thin-film transistors (TFTs) to overcome these challenges. Notably, AlOx was successfully formed without degrading the AOS TFTs owing to the polymer buffer layers. The hybrid passivation approach ensured the satisfactory stabilization of the TFTs under bias stress owing to the high isolation effect, which could prevent the penetration of environmental molecules. This passivation method can facilitate the application of solution-processed AOSs in integrated circuits.