<p>Acrylonitrile-based polymers are widely used in industrial and consumer settings, contributing to the growing amount of plastic waste. Yet, their chemical recycling has largely been neglected, partly due to the potential release of harmful gases such as HCN and NOx. Herein, we report a catalytic process that enables valorization of the polymer’s N- and C-content, without releasing harmful nitrogen gases. Our strategy uses Pd-based shuttle catalysis to transfer HCN units from the polymer’s backbone to an olefin acceptor molecule, generating a carbonaceous polyolefin residue amenable to further upcycling, alongside a useful nitrile building block. The protocol can be optimized in two ways: to efficiently functionalize olefins and produce nitriles in up to quantitative yields as a safe, cost-effective alternative to commonly employed nitrile synthesis methods, and to fully dehydrocyanate polymers using ethylene as HCN acceptor. Furthermore, we demonstrate the applicability of our strategy for the upcycling of commercial polyacrylonitrile materials.</p>