1,1,3,3,5,5,7,7‐Octamethyltetrasiloxane (HMD2MH), which is reported to release Me2SiH2 via a B(C6F5)3‐catalyzed redistribution, acts as a good Me2SiH2 precursor in the B(C6F5)3‐catalyzed dehydrocarbonative condensation of alkoxysilanes. A series of oligo(dimethylsiloxane‐co‐diphenylsiloxane)s that are uniformly sized and sequence‐defined at the atomic level are synthesized by a one‐pot controlled iteration of a B(C6F5)3‐catalyzed dehydrocarbonative condensation of alkoxysilanes with HMD2MH or Ph2SiH2 and a B(C6F5)3‐catalyzed hydrosilylation of carbonyl compounds, followed by the subsequent B(C6F5)3‐catalyzed dehydrogenative condensation of silanols.