6061 Al/Cu layered composites were fabricated by accumulative roll bonding (ARB). The microstructural evolution was examined using scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. After seven ARB cycles, the tensile strength increased to 416 MPa, whereas the elongation decreased to 6.7%. The strength enhancement is mainly attributed to work hardening and grain refinement. No brittle intermetallic compounds (IMCs) were detected at the interface, and interfacial bonding improved with additional ARB cycles. The small hardness difference between Al and Cu promoted uniform plastic deformation across layers, enhancing interfacial cohesion. However, strain localization due to different work hardening responses of Al and Cu led to pronounced shear band formation after seven ARB cycles, reducing the plasticity.