Precise control of primary chemical structures, especially those of complex structures, is a prerequisite to understand the structure–property relationships of functional macromolecules. In this article, we report the rational design and tandem synthesis of three asymmetric giant gemini surfactants (AGGSs) of complex macromolecular structures based on polyhedral oligomeric silsesquioxane (POSS). In two cascading processes (typically within 5 hours), AGGSs can be synthesized where the length of the two polymer tails and the identity of the two POSS heads can be independently controlled and systematically varied. It represents a convenient, efficient, and modular way to prepare giant molecules with rigorous structural precision in only a few steps. This study expands the scope of synthetically available giant surfactants and facilitates further structural evolution toward even more complex macromolecules.