Ion mobility and ion concentration are the two key factors governing ionic conductivity of a polymer; the former is not only directly related to the identity and quantity of cations and anions, but is also greatly affected by the physical and chemical characteristics of the polymer matrix bearing the ions. Polymers with low glass transition temperature and low crystallinity are good candidates to achieve high ionic conductivity at room temperature for practical applications. However, polyelectrolytes are predominantly made of polymers containing high polarity backbones to facilitate ion dissociation, which raise the glass transition temperature or promote crystallinity by increasing intermolecular interactions. In contrast, polymers with low dielectric constants, like PDMS, have low glass transition temperatures and maintain an amorphous state, but are barely ionically conductive without modification lations to unveil ion conducting mechanisms in metal-coordinated PDMS. A low molecular weight polydimethylsiloxane (PDMS) end-functionalized with pyridyl imine ligands is selected as the model system, and a series of Li and Cu salts are added to form polymer complexes. Factors that govern the ionic conductivity of the material, including ion dissociation, ion concentration, and chain mobility, are discussed in the context of the metal-ligand coordination density and strength. Firstly, we highlight that the formation of metal-ligand coordination promotes salt dissociation into ions and therefore enhances the ionic conductivity of the PDMS complex as compared to the direct mixing of pristine PDMS and metal salt. Next, we show that the choice of counter anion, metal cation, and ion concentration can vary the ionic conductivity of PDMS by orders of magnitude due to the distinct cation-anion interactions. To elucidate the ion transport mechanisms, a range of properties are computed from the MD simulations, including the ion and polymer chain diffusion coefficients, ionic conductivity, and cluster analysis. Furthermore, based on our observations of the single metal cation coordinated PDMS, we propose and prove that a synergistic effect on the mechanical strength and ionic conductivity of the PDMS would be achieved by coordinating with two metal cation species: the majority component is the metal cation with weak coordination, that is primarily responsible for the ion conductivity; whereas the minority component is the metal cation with strong coordination that enhances the mechanical strength of the network. This paper provides insights into strategic design of ionically conducting polymers that would benefit a range of applications.