Novel submicrometer-scale flat carbon fibers (SFCF) have been synthesized by catalytic chemical vapor deposition of acetylene over an Ni-Al layered double hydroxide (NiAl-LDH) compound, and the electrochemical activity of Pt supported on as-synthesized SFCF for methanol oxidation has been investigated. The materials were characterized by power X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, and cyclic voltammetry tests. The results reveal that the active crystal facets of the NiAl2O4 spinel phase derived from NiAl-LDH can deposit carbon atoms to grow SFCF, and that the co-growing Ni nanoparticles are not catalytically active for the formation of SFCF. Furthermore, after support with Pt, the resultant Pt/SFCF electrocatalyst shows much higher activity for methanol oxidation than the Pt/C one in both acid and alkaline media, which is attributed to the combined beneficial effects of the microstructure of the SFCF support, improved electrical conductivity originating from the NiAl2O4 spinel catalyst embedded in SFCF, and improved dispersion of Pt particles through exposed Ni nanoparticles adhering intimately to the SFCF.