By exploiting the desired properties of different materials, a heterostructure can be tailored to acquire optimal functionality for a specifi c device. Heterojunction formation in semiconductor nanowires (NWs) is crucial for many predicted applications in nanoscale optoelectronics. [1][2][3] Recently, a lot of effort has been devoted to developing new methods to integrate heterointerfaces in the growth of semiconductor NWs. Several groups have fabricated various semiconductor NWs with a coaxial or biaxial heterostructure, such as GaInAs/ AlInAs coaxial NWs [ 4 ] and ZnS/Zn 2 SnO 4 biaxial NWs. [ 5 ] Hsiao et al. also recently reported the synthesis of ZnSe/ ZnCdSe heterostructured NWs using the vapor-liquid-solid (VLS) method via the molecular beam epitaxy (MBE) technique. [ 6 ] Among the syntheses of heterostructured semiconductor NWs, the realization of magnetic/nonmagnetic heterostructured NWs would be even more important since they could serve as a building block for more complex and sophisticated devices, such as 1D magnetic transistors. Oka et al. have recently reported that NiO/MgO heterostructured NWs show a substantial discrepancy of up to four orders of magnitude between the resistivity of the heterostructured NWs and that of the hetero thin fi lms. [ 7 ] Recently, considerable effort has been devoted to the study of transition-metal selenide nanostructures due to their interesting physical and chemical properties and wide variety of potential applications. [8][9][10] Nickel selenides are the typical Pauli paramagnets with metallic conductivity, and have been regarded as typical materials for studies of the physical characteristics associated with a narrow-band electron system. [ 11 ] They are also potential materials for photoelectrochemical solar cells and catalysts. [ 12 , 13 ] Nickel and selenium can form a variety of nickel selenides, such as the three homogeneous and stable phases NiSe, NiSe 2 , and Ni 3 Se 2 , but other phases, such as Ni 2 Se 3 , Ni 2 Se, and Ni 3 Se 4 , have also been suggested. Studies on a number of nickel selenide-based nanostructures have recently been reported. [14][15][16] In recent years,