This chapter presents amphiphilic polymer co-networks (APCNs) fabricated as functional membranes and will illustrate related applications. First, the structural features of APCNs rendering them ideal membrane materials will be described. Applications as membranes with a functional performance that is directly based on these structural features are presented. Next, the preparation of co-network membranes based on stimuli-responsive polymers and their potential for smart membrane systems are detailed. Finally, the functionalisation of co-network membranes with stimuli-responsive units such as organic photochromes and applications as light-responsive or even multi stimuli-responsive drug delivery membranes are described.