Cyclic tetramers of 3,7-dibenzo[b,d] thiophene (DBT) and 3,7-dibenzo[b,d]thiophene-5,5-dioxide (DBTO), i.e., [4] cyclo-DBT ([4] CDBT) and [4] cyclo-DBTO ([4] CDBTO), respectively, are synthesized by the platinum-mediated assembly of bis-metallated DBT and DBTO and the subsequent reductive elimination of platinum. This is the first example of the synthesis of sulfur-containing cycloparaphenylene (CPP) derivatives. The structure of [4] CDBTO is unambiguously determined by the single crystal X-ray analysis. Theoretical and experimental analyses of their physical properties reveal the effect of the sulfur atom and sulfonyl group at the periphery of biphenyl units of the CPP.