This paper develops ICDP Network Cosmology, a theoretical framework in which the multiverse is modeled as a structured communication network governed by the Invariant Causal Decomposition Principles. In this approach, every spacetime manifold carries an ICDP invariant tensor whose conservation law and associated gradient field determine the causal structure and physical constants of each universe. Distinct universes appear as nodes in a weighted graph connected by gradient transmission channels. We show that the resulting multiverse network is scale free, with a degree distribution fixed by the ICDP nucleation rate. A generalized transport equation describes gradient flow across universe boundaries, and a global continuity law ensures conservation of causal charge across the full network. We prove the Network Governance Theorem, which states that the topology of the multiverse is uniquely determined by the spectrum of the ICDP invariant operator. The network evolves under a multiverse scale entropy principle and satisfies an ICDP H theorem that guarantees convergence toward a fixed point attractor. Three observational signatures follow from the theory: low multipole CMB modulations, an ultra low frequency gravitational wave background, and a characteristic primordial black hole mass spectrum. ICDP Network Cosmology provides a unified and predictive framework for multiverse organization, gradient transmission, and the large scale structure of cosmic communication.