Multi-walled carbon nanotubes (MWCNTs) were treated with γ-ray irradiation to show enhanced interaction with polyamide 6,6. X-ray photoelectron spectroscopy and Raman spectroscopy revealed that oxygen atoms were found on the surface of the MWCNTs, which can enhance the interaction with hydrophilic polymers such as polyamide 6,6. Both morphological investigation and electrical conductivity measurements have demonstrated better dispersion and electrical percolation with a smaller amount of MWCNTs when they were subjected γ-ray irradiation. The electrical percolation thresholds were reduced from 0.934 wt% to 0.401 wt% and 0.332 wt% when MWCNTs were irradiated with 10 and 30 kGy, respectively. Rheological data showed consistent behavior, exhibiting a positive effect of γ-ray treatment on MWCNTs. Allowing large volume treatment in a simple, solvent free process, the proposed γ-ray irradiation based method is potentially suitable for further commercialization.