Overall goal of this research is to study the conductivity enhancement effect and its mechanism for different types of carbon-based nano-fillers/conduct polymer hybrids in carbon fiber reinforced polymer (CFRP). Multi-walled carbon nanotubes (MWCNT)/polyaniline (PANI) and graphene oxide (GO)/PANI hybrids were separately dispersed into divinylbenzene (DVB) to make the CFRP composites. The alternating current (AC) electrical conductivity results show that both, the binary MWCNT/PANI and GO/PANI hybrids have significant enhancement on AC conductivity, while MWCNT/PANI gives better improvement over GO/PANI hybrids. The mechanism for the conductivity enhancement was studied by SEM, XRD, UV–Vis and nanoindentor. Circuit models were proposed. The maximum AC conductivity of CFRP made of MWCNT/PANI was measured to be 22.4 S/m, which has been found to be enhanced by more than 3 orders of magnitude compared to CF/DVB. Thus, CF/MWCNT-PANI composites can be considered to be promising candidates for multifunctional material where high conductivity is demanded.