The first synthesis of macrocyclic α-ABpeptoids with varying lengths is described. X-ray crystal structures reveal that cyclic trimer displays a chair-like conformation with a <i>cct</i> amide sequence and cyclic tetramer has a saddle-like structure with an uncommon <i>cccc</i> amide arrangement. The creation of a DNA-encoded combinatorial library of macrocyclic α-ABpeptoids is described.