Pilot-fueling and nozzle-injection pressure are significant injection parameters, and they have significant impacts on modern vehicles for enhancing the engine output, in addition to meeting rigorous tailpipe-exhaust emission standards. In this current work, the influence of the pilot-fueling pressure and nozzle-opening pressure (NOP) on the engine performance and tailpipe outcomes from a compression-ignition (CI) engine at a higher injection pressure and varying load conditions was investigated using a waste cooking oil (WCO) biodiesel (B20). The experiments were executed in a high-pressure CRDi-fitted diesel engine at the start of pilot fueling (SOPF) (timing: 23° bTDC), and at the start of the main fueling (SOMF) (timing: 33° bTDC). The results showed that the combined influence of the pilot-fueling and nozzle-opening pressure induced a remarkable enhancement in the BTE, by 25.13%, and the BSFC decreased by 13.88%, compared with diesel at 10% pilot fueling. Carbon monoxide, hydrocarbon, and smoke emissions were drastically reduced for the higher pilot-fueling quantity by 21.05%, 16.66%, and 33.10%, respectively, compared with the diesel at 10% pilot fueling. With the implementation of the pilot-fueling strategy, there is no effect on the NOx reduction.