Abstract The Λ-Cold Dark Matter (ΛCDM) model, the standard framework of modern cosmology, has achieved unprecedented agreement with observational data from the cosmic microwave background (CMB), large-scale structure, and Type Ia supernovae. However, it suffers from a fundamental, unresolvable flaw: the initial Big Bang singularity, where general relativity (GR) predicts infinite energy density, infinite temperature, and the breakdown of all known physical laws. This non-physical divergence has long been the core crisis of cosmological origin theory. In this work, we propose a novel Inter-Void Domain Wall Tunneling (IVDWT) model, a singularity-free cosmological framework rooted in quantum field theory (QFT) and topological defect dynamics. We define a landscape of causally disconnected primordial voids: independent spacetime regions each with a unique quantum vacuum ground state, separated by topological domain walls (inter-void boundaries). We demonstrate that a quantum field in a higher-energy parent void can tunnel through the domain wall into a lower-energy daughter void (our observable universe). The so-called "Big Bang singularity" is not a physical point of infinite density, but a zero-dimensional topological tunneling channel through which the total mass-energy of our universe is injected from the parent void. This model naturally eliminates the initial singularity, resolves the horizon and flatness problems without ad-hoc inflationary fine-tuning, and is fully consistent with all existing ΛCDM observational constraints. We further derive three testable observational predictions that can be verified by upcoming CMB-S4, LISA, and Simons Observatory surveys, providing a clear path to falsification or validation. This framework provides a physically consistent, mathematically rigorous description of cosmic origin, avoiding the non-physical infinities of the standard singularity paradigm. Keywords: Theoretical Cosmology; Singularity-Free Universe; Quantum Tunneling; Topological Domain Walls; Primordial Void Landscape; Cosmic Microwave Background Anisotropies