A noncylindrical cycloarylene was designed with [4]helicene as an arylene panel and was assembled by R/S-biaryl linkages. By determining the molecular structures of four stereoisomers (3 diastereomers and 1 enantiomer pair), we found that the structural mathematics of congeners can be best described by R/S-configurations of biaryls and not by panel orientations. Comparisons with structurally relevant cycloarylenes deepened our understanding of cyclostereoisomerism and structural chemistry.