Plant terpenes have proven to be effective in stimulation of polychlorinated biphenyls (PCBs) biodegradation in soil systems. However, data on the application of plant terpenes in marine sediments contaminated with PCBs remains limited. The aim of this study was to ascertain the roles of a PCB degrading consortium and plant terpenes in stimulation of PCB biodegradation in marine sediments. The consortium culture 1-2Mix (strains 1-2M and 1-2T in commensalism), a utilizer of biphenyl and a natural substrate was enriched and isolated from marine sediments from the Busan coast, South Korea. PCB degradation by this culture was shown to be more effectively induced by tangerine peel extract than other known substrates (limonene, pinene, and cymene). Coastal sediment microcosms inoculated with 1-2Mix were set up to elucidate the effect of the consortium and plant terpenes on degradation of Aroclor 1242. After four weeks, the highest removal rates of PCBs, compared with the control (autoclaved sediment and no inoculation of 1-2Mix), were observed in order of the inducers tested; biphenyl (71.1%), tangerine peel extract (69.5%), surfactant (66.0%), and limonene (63.0%). Bioaugmentation effect was doubled in the presence of natural substrates such as tangerine peel extract and limonene, indicating effectiveness of these substrates in biostimulation. It was concluded that the tangerine peel extract could replace biphenyl as a feasible induction substrate for effective remediation of PCBs in the marine sediment.