In this paper, Co-Al layered double hydroxide (LDH) and carbon nanotubes (CNT) have been assembled to form exfoliated LDH nanosheet/carbon nanotube hybrids via electrostatic force. The assembling process and nanostructures of exfoliated LDH/CNT hybrids were investigated by zeta potential, Raman spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The assembly mechanism of LDH with CNT was also discussed. Furthermore, the unique three-dimensional (3D) hybrids thus prepared were used as reinforcing nanofillers to enhance the performance of polyamide 6 (PA6). It was found that the synergic effect of the CNT and LDH nanoplatelets resulted in homogeneous dispersion of the hybrid nanofillers throughout the PA6 matrix and strong combination with the matrix, thus providing an efficient mechanical improvement for the PA6 nanocomposites.