Thioesters are critical chemical intermediates in numerous extant biochemical reactions and are invoked as key reagents during prebiotic peptide synthesis on an evolving Earth. Here we asked if a thioester could replace the native oxo-ester in acyl-tRNA substrates during protein biosynthesis by the ribosome. We prepared 3′-thio-3′-deoxyadenosine triphosphate in 10 steps from xylose and demonstrated that it is an effective substrate for the E. coli CCA-adding enzyme, which appends 3′-thio-3′-deoxyadenosine to truncated tRNAs ending with 3′-CC. Using a variety of aminoacyl-tRNA synthetases, flexizymes, or a direct thioester exchange reaction, we prepared a suite of 3′-thio-tRNAs acylated with α- and non-α-amino acids. All were recognized and utilized by wild-type Escherichia coli ribosomes during in vitro translation reactions to generate oligopeptides in yields commensurate with native oxo-ester tRNAs. These results indicate that thioester intermediates widely used in Nature can be co-opted to support the incorporation of natural α-amino acids as well as non-canonical monomers by the extant translational machinery for sequence-defined polymer synthesis.