A new highly selective method for the synthesis of borasiloxanes through the O-borylation of silanols, disilanols, and disiloxanediols with vinylboronates in the presence of Ru0 complexes (mainly Ru3CO12) is described. The method leads to the formation of special compounds with a B–O–Si inorganic framework. When Ru0 complexes are used as a catalyst, no vinylboronate homocoupling is observed. A mechanism