Abstract <p>Graphene has an extraordinarily high thermal conductivity which is dictated by the long-wavelength acoustic phonon and dimensional confinement effects. Traditional descriptions using molecular dynamics and Boltzmann transport theory can model size and temperature scaling, but require detailed phonon dispersions and mode-resolved lifetimes as inputs. Here we introduce a cohesive-energy-based transport formalism that provides a direct energetic-to-thermal mapping in finite graphene nanostructures. Beginning with cohesive-energy renormalization with edge atoms, we obtain the respective change in elastic stiffness, acoustic phonon velocity, Debye temperature, intrinsic mean free path, lattice thermal conductivity in a single, analytical form. The resulting closed-form expression captures length-dependent logarithmic scaling, width-induced saturation, chirality-dependent anisotropy, and temperature-induced Umklapp suppression without solving the complete phonon Boltzmann equation. The model shows quantitative consistency with representative experimental and theoretical data and offers a physically transparent, reduced-order description of ballistic-to-diffusive transport crossover in two-dimensional systems. This energetic renormalization methodology bridges the gap between atomistic stability and continuum heat conduction and provides a scalable model to study thermal transport in graphene-based nanostructures.</p>