In July 2023, the International Maritime Organization (IMO) presented an updated strategy for decarbonizing maritime transport and achieving net-zero greenhouse gas emissions by 2050. It is therefore imperative to explore innovative solutions to achieve a blue economy and maximize energy efficiency on-board ships. For this reason, the current study aims to integrate the organic Rankine cycle (ORC) and thermoelectric generator (TEG) on board a container ship to generate electrical energy and reduce fuel consumption. The combined system will benefit from the waste heat of a marine diesel engine installed on board. The current study uses R245fa as the organic liquid and analyzes the effects of varying the evaporation pressure on the energetic and economic performance indicators by modeling the combined system in Engineering Equation Solver (EES) software. The results show that the energy efficiency of the ORC system increases from 12.3% at 3.5 bar to 17.3% at 8 bar. In comparison, the energy efficiency of the TEG unit is 6.9% at different evaporation pressures. In addition, the energy efficiency of the TEG-ORC system is 18.3% with an output of 1386 kW at 8 bar, which is an increase of 30.5% compared to the value at 3.5 bar. This generated power reduces fuel consumption by around 1580 ton/year. From an economic point of view, the energy production cost of the combined system is USD 618/kWh and USD 614/kWh at the lowest and maximum evaporation pressure, respectively. Fuel costs and CO2 tax expenditures could be reduced by up to USD 1.169 million/year and USD 0.47 million/year, respectively, through the combined TEG-ORC system.