Diamond, an ultrawide-bandgap semiconductor material, is promising for solar-blind ultraviolet photodetectors in extreme environments. However, when exposed to high-temperature conditions, diamond photodetector surfaces are unavoidably terminated with oxygen, leading to low photoresponsivity. To address this limitation, single-crystalline diamond nanowires (DNWs) embedded with platinum (Pt) nanoparticles were developed using Pt film deposition followed by chemical vapor deposition (CVD) homoepitaxial growth. During the CVD, Pt nanoparticles (approximately 20 nm in diameter) undergo dewetting and become uniformly embedded within the single-crystalline DNWs. Photodetectors fabricated with these Pt nanoparticles-embedded DNWs achieve a responsivity of 68.5 A W⁻¹ under 220 nm illumination at room temperature, representing an improvement of approximately 2000 times compared to oxygen-terminated bulk diamond devices. Notably, the responsivity further increases with temperature, reaching an exceptional value of 3098.7 A W⁻¹ at 275 °C. This outstanding performance is attributed to the synergistic effects of the one-dimensional nanowire structure, deep-level defects, the localized surface plasmon resonance effects induced by embedded Pt nanoparticles, and localized Schottky junctions at the Pt/diamond interface, which enhance optical absorption, carrier generation, and separation efficiency. These results highlight the significant potential of Pt nanoparticles-embedded DNWs for advanced deep ultraviolet detection in harsh environments, including aerospace, industrial monitoring, and other applications.