Here we report a new methodology for mRNA-programmed synthesis of peptoids and peptoid-peptide hybrids by means of translation machinery under the reprogrammed genetic code. We initially screened N-substituted glycines (rGly) for their single incorporation into a nascent peptide chain and found translation machinery accepts a variety of rGly for elongation. Moreover, we have shown consecutive elongations of rGly and mRNA-directed synthesis of cyclic peptoid-peptide hybrids. This methodology offers a powerful tool for mRNA-programmed library synthesis of peptoids and peptoid-peptide hybrids with linear and cyclic scaffolds, potentially leading to the discovery of drug candidates with proteolytic stability and membrane permeability.