This paper constructs a logically self-consistent emergent structural frameworkfor the Many-Worlds Interpretation (MWI) based on decoherence theory, quantum information geometry, and self-referential dynamics. Within this framework,a ”world” is rigorously defined as a quasi-classical branch formed in Hilbert spacethrough environmental decoherence and information-geometric boundaries. Its independence is quantitatively characterized by the branch separation degree Dab defined by the quantum relative entropy between branches. When Dab exceeds a critical value Dc determined jointly by the energy scale of environmental fluctuationsand the decoherence time, the branches separate irreversibly in the informationgeometric sense, constituting independent ”worlds”. Furthermore, by introducingthe concept of a self-consistent observer, this paper demonstrates the dynamic selection mechanism of cosmological laws within the string theory landscape: only thosevacuum branches that can support self-consistent observers (satisfying conditionssuch as the memory decoherence time being much greater than the cognitive operation time) have their wavefunction weights effectively preserved during evolution,thereby acquiring physical reality. Finally, combining Zurek’s envariance argumentwith the requirement of observer memory stability, we show that the Born ruleP(i) = |⟨i|ψ⟩|2 is not an additional assumption but a necessary consequence forthe stable existence of self-consistent observers. This framework provides an operational mathematical foundation for the many-worlds interpretation, transforms theanthropic principle into a dynamic selection problem, and offers an explanation forthe origin of probability based on quantum information principles.