Platinum is a face centered cubic structured crystal that has been widely known as a superior catalyst for various chemical reactions, while low-dimensional structures, such as mono- or bi-layer platinum, have attracted less attention due to experimental difficulties in synthesizing such 2D structures. In this study, for the first time, we present a computational research on the unique architecture of epitaxial platinum (mono/multi) layers grown on graphene (Pt_ML/GR), in support of remarkable recent progress in the synthesis of these architectures in simple cubic-like (SC-L) and face-centered cubic-like (FCC-L) phases on the graphene. In these architectures, Pt exhibits registry with the C-C bridge sites along the armchair and zigzag directions. Here, the detailed band structure and the partial/total densities of state (DOS) of the Pt_ML/GR architectures, with Pt in an SC-L registry, is presented. Pt atoms on graphene prefer bonding with two carbons covalently, turning C-C sp2 bond to sp3 bond, while metallic bonding prevails on the Pt atoms. Investigation of the hybrid bonding configuration and electronic properties requires well-described ground-states of the metallic and covalent bonding configuration, simultaneously. Recently proposed strongly constrained and appropriately normed (SCAN) density function study (DFT) is employed to investigate the structural and electronic properties of the epitaxial SC-L Pt layered graphene. First, the epitaxial geometry of Pt layers as well as inter-layer distance between graphene and Pt layer are in good agreement with the experimental observations. Second, the covalent bond character is observed between Pt and C while Pt layer attains the metallic bond character. Furthermore, as an application for electrochemical system such as fuel cells, the efficacy and the stability of Pt ML/GR catalysts under the canonical oxygen reduction reaction are presented.