In the view of the fact that catalytic routes to design functionalized silsesquioxanes are currently of high importance, herein we report the effective functionalization procedure to obtain mono-, di-, and tetrasilylalkynylsubstituted silsesquioxanes of cubic T 8 and DDSQ type. The synthetic methodology is based on Ru-hydride complex that turned out to be an efficient catalyst for silylative coupling of ethynylsiloxysubstituted silsesquioxanes with vinylsilanes resulted in their silylalkynyl analogues. The ethynylsiloxysubstituted double-decker silsesquioxanes have been noted to be reactive in this process for the first time. A series of novel compounds were obtained, isolated, and characterized. Due to the presence of silylalkynyl moieties, they constitute an interesting family of Si−O−Si-based unique structures with potential applications.