Recent developments on supported Ni-Fe alloy catalysts are reviewed for various reforming reactions such as dry reforming of methane and steam reforming of molecules larger than methane. The catalytic performance greatly depends on the preparation methods, because the control of the composition of the Ni-Fe alloy is critical. Simple co-impregnation is not effective in obtaining uniform Ni-Fe alloy particles. Impregnation of Ni on Fe-containing mixed oxide supports can give Ni-Fe alloy particles by reduction; however, the control of the Fe/Ni ratio is rather difficult. On the other hand, utilization of oxide precursors containing both Ni and Fe ions such as hydrotalcite-like compounds and perovskite is effective in obtaining Ni-Fe alloy particles with controlled composition. The optimized Ni-Fe alloy catalysts show good performance in various reforming reactions in view of activity and resistance to carbon deposition. In addition, catalysts prepared from oxide precursors containing both Ni and Fe ions can show good regeneration ability by re-dispersion during the oxidation-reduction treatment.