A numerical study was carried out to investigate the effects of injector spray angle (SA) and injection position (IP) on the combustion and emission characteristics of a two-stroke ME-GI marine engine at full load. Three-dimensional (3D) simulations of the combustion process and emission formations inside the cylinder of the engine operating in the diesel and DF modes were performed using the ANSYS Fluent simulation software to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were compared and showed good agreement with the experimental results reported in the engine’s shop test technical data. The simulation results showed that the IP of 0.02 m with an SA of 40 degrees helps to enhance the engine performance; however, if the main target is reducing engine exhaust gas emissions, an IP of 0.01 m is highly recommended to be used. At this IP, the specific SA of 40, 45, or 50 degrees that should be used will depend on which emissions (NO, soot, CO2, etc.) need to be reduced. This study successfully investigated the effects of injector SA and IP on the combustion and emission characteristics of the researched engine and would be a good reference for engine design and operating engineers.