Precise control over the monomeric sequence on natural sequence-defined polymers (SDPs) leads to their structural diversity and functions. However, absolute control over the monomeric sequence on a synthetic polymer remains a challenging process. Herein, we describe a support-free, protection-deprotection-free, cost-effective, and fast iterative strategy for multigram production of a new class of SDP with a unique functional group, dithiocarbamate, a potential group for material and biomedical applications. The strategy is based on a unique monomer, named as amine-hydroxyl monomer, and a three-component reaction between the monomer, CS2, and terminal chloro group of the growing chain. The fast strategy allows us to synthesize a 5-mer sequence-defined oligomer in 6 h. For a proof of concept, a range of aliphatic and aromatic groups have been incorporated at different sequences in the sequence-defined oligomer. This SDP platform has further been advanced by two ways: (i) multiple approaches for postsynthetic modification of SDP and (ii) increasing the chain length in a single step. © 2020 American Chemical Society.