To address the “dead layer” effect in conventional 4H-SiC α-particle detectors, where thick metal Schottky electrodes (typically tens to hundreds of nanometers) cause substantial energy loss of incident α particles and significantly degrade energy resolution, this study proposes an innovative design that employs atomically thick graphene as both the Schottky contact electrode and the entrance window. This approach aims to effectively suppress dead-layer energy loss and enhance detector energy resolution. The investigation begins with SRIM simulations to evaluate the energy-loss characteristics of various electrode materials for 5.486 MeV α particles from a ²⁴¹Am source. For 100 nm-thick Ni and Au electrodes, the energy losses at normal incidence are 38.36 keV and 43.50 keV, respectively, and increase sharply with incident angle. In contrast, graphene electrodes exhibit energy losses consistently below 0.04 keV. Subsequently, Geant4 simulations of α-particle energy deposition spectra under uniform incidence within a conical solid angle (half-angle 0–π/3) indicate that the dead-layer contributions from Ni and Au electrodes to energy resolution are 0.37% and 0.46%, respectively (accounting for 37% and 46% of the typical ~1% energy resolution for 4H-SiC α detectors), whereas graphene’s contribution is only 0.03%, quantitatively confirming its capacity to substantially reduce spectral peak broadening caused by energy loss. Experimentally, monolayer graphene grown by chemical vapor deposition (CVD) is transferred onto the surface of a 4H-SiC epitaxial layer using a PMMA-assisted wet transfer process, resulting in a graphene/4H-SiC Schottky α-detector prototype. Raman spectroscopy confirms successful high-quality graphene transfer, as evidenced by prominent G and 2D peaks, and electrical measurements demonstrate excellent rectifying characteristics and low noise levels. Irradiation experiments with a ²⁴¹Am α source conducted in air produces a clear α energy spectrum peak near 5.4 MeV (after accounting for air-gap energy loss), achieving an energy resolution of 4.64% (closely matching the Geant4-simulated value of 4.22%) and validating the composite spectral structure in which some α particles achieve near-full energy deposition. The core innovation of this work lies in the integrated validation through SRIM/Geant4 simulations, device fabrication, and α-spectrum testing, which quantitatively elucidates the mechanism by which graphene electrodes suppress dead-layer energy loss and demonstrates their feasibility as ultrathin entrance-window Schottky electrodes for 4H-SiC α detectors. This research establishes a robust theoretical and experimental foundation for the future development of high-energy-resolution graphene/4H-SiC α detectors suitable for high-temperature and high-radiation environments, while offering new pathways for electrode optimization in wide-bandgap semiconductor radiation detectors.