Magnetic double-shelled Ag@C@Co pentagonalprism nanocables are fabricated using a synchronous growth and oriented assembly process, in which the second shell of Co is arranged along the edges of Ag@C pentagonalprism nanowires (NWs). The resulting Ag@C@Co pentagonalprism nanocables exhibit an average diameter of 400 nm and consist of Ag core NWs with diameter of 200 nm and C middle layers with a thickness of 10 nm as well as outer Co shells with a thickness of 100 nm. UV-vis absorption spectroscopy shows that the Co shell on Ag@C NWs can damp the surface plasmon resonance (SPR) of the Ag core wires and lead to a red-shifted SPR absorption peak. Additionally, the Ag@C@Co nanocables have the ferromagnetic behavior, which can be controlled by modulating the shell density. The resulting magnetic Ag@C@Co nanocables exert excellent selected catalytic activity along the edges toward the dehydrogenation of ammonia borane aqueous under ambient conditions at room temperature.