This paper introduces a novel energy-harvesting hydraulically interconnected suspension (EH-HIS) to improve the riding comfort and road handling performance for off-road vehicles while harvesting the vibration energy traditionally dissipated into heat by the oil shock absorbers. To understand the system, we built a model of the off-road vehicle equipped with the EH-HIS and conducted the performance analysis. The system model is established based on the pressure drop principle and validated by commercial simulation software AMESim. The damping characteristic and energy harvesting performance have been investigated based on the mathematical suspension model. Further, a thorough analysis is implemented to compare the dynamic responses of the vehicle equipped with the traditional suspension and EH-HIS under different driving speeds and road classes. Results show that the EH-HIS system can provide tunable asymmetric damping from 3134 Ns/ to 7558 Ns/m, which covers most of the damping range of the off-road vehicles. The average regenerative power of the half EH-HIS system reaches 438 watts, and the corresponding hydraulic efficiency reaches 19%, at a vibration input of 2 Hz frequency and 30 mm amplitude. The ride analysis shows that the vehicle equipped with the EH-HIS system on the D class road has good handling stability and better ride comfort over the traditional suspension.