Off-highway vehicles, with their unique requirements of durability, high power, and torque density, are typically powered by diesel ignition internal combustion engines (ICEs). This reliance on ICEs significantly contributes to greenhouse gases (GHGs) emissions. For this reason, there is an urge to develop an energy-efficient powertrain architecture that produces fewer GHGs emissions while meeting the variable torque levels and variable speeds and performing various duty cycles with high efficiency. In order to select the energy-efficient powertrain architecture for the off-highway vehicle, different existing powertrain architectures (i.e., series hybrid, parallel hybrid, series-parallel hybrid, conventional) for off-highway applications have been studied to highlight their pros and cons. This is done considering the different duty cycles and applications along with Life Cycle Analysis (LCA). Off-highway vehicles operate under different road/surface conditions than on-road vehicles, which affects the powertrain’s performance. Hence, the terrain properties are also discussed and considered in this work to select the appropriate powertrain architecture. The selected powertrain architecture takes into account the above-mentioned loads to ensure better performance. Lastly, the authors present the details of the proposed powertrain architecture for off-highway vehicles in this manuscript, including its components, architecture, and modes of operation. The proposed architecture is compared with the conventional off-road vehicle’s architecture to highlight its benefits, including energy benefits and fuel consumption benefits, that lead to GHG emissions reduction benefits.