Aniline is an important chemical raw material widely used in various industries, including medicine, dye manufacturing, and rubber production. Catalytic liquid-phase dhydrogenation of nitrobenzene is a main industrial production method for aniline. However, the separation and recovery of the catalyst from the liquid hydrogenation system remain challenging. Graphene-encapsulated transition-metal nanoparticles (TM@G, where TM = Fe, Co, and Ni) exhibit magnetic separability and electron transfer effects, making them widely applicable in heterogeneous catalysis. In this study, a magnetically separable catalyst support, comprising graphene-encapsulated Ni nanoparticles (Ni@NG), was developed. This support was then loaded with a Pt metal catalyst for efficient catalytic hydrogenation of nitrobenzene to aniline. To fabricate the catalyst support, ethylenediaminetetraacetic acid and Ni(OH)₂ were uniformly mixed in deionized water until the solution turned blue at 90°C. The resulting blue solid precursor was then dried and annealed at 600°C in argon to yield the magnetic support (Ni@NG). The support was then characterized using Raman spectroscopy, TEM, XRD, and XPS. TEM results revealed that the Ni@NG support exhibited a typical core-shell structure (with nanoscale Ni particles as the core and 2-5 layers of graphene as the shell). The Raman spectrum of the Ni@NG support exhibited the characteristic D and G bands of graphene at 1341 and 1604 cm^-1, respectively. Moreover, the XRD spectrum of this support exhibited distinct peaks corresponding to Ni and graphene, while its XPS analysis confirmed the presence of an approximate nitrogen atom concentration of 3.64% in the nitrogen-doped graphene shell. Furthermore, the deposition-precipitation method was employed to synthesize a Pt-loaded Ni@NG catalyst (Pt/Ni@NG), which was later used in the catalytic hydrogenation of nitrobenzene in a liquid-phase reaction. Results revealed that increasing the Pt weight loading (mass fraction) from 0.1% to 0.5% altered the Pt dispersion state from single atoms to clusters and then to particles. In particular, at a Pt weight loading of 0.3%, the Pt/Ni@NG catalyst dominated by Pt clusters exhibited the highest activity for the hydrogenation of nitrobenzene. At this Pt weight loading, the catalyst achieved a turnover frequency of 27239.2 h^-1 at 1 MPa reaction pressure under 30°C, completely converting nitrobenzene to aniline within 60 min. Furthermore, the Pt/Ni@NG catalyst maintained its activity over five testing cycles, attributed to its excellent liquid-phase magnetic separability.