A two‐stage inverse model for the design of gate‐all‐around nanowire metal oxide semiconductor field effect transistors (MOSFETs) is proposed in this article. The proposed model first validates the selection of output characteristics using a normalizing flow based generative model, and then predicts the device parameters corresponding to the valid output characteristics using a cascade of inverse and forward artificial neural networks (ANNs). This accurately captures any out‐of‐distribution datapoint in the output characteristics distribution and computes the device parameters through the inverse ANN, avoiding any conflicts created by non‐unique mappings. The two‐stage model instantly predicts possible device designs for a target output characteristic set without going for multiple iterations to arrive at a device‐design, highlighting the accuracy and robustness of the model.