Abrasive Water Jet Machining Process (AWJM) is a modern machining technique that is excellent for cutting materials of all hardness, from Inconel to rubber. The present study addresses machining parameters’ effects on surface roughness of stainless steel grade 316L during cutting by AWJM. For the trials, three different levels of each of the machining parameters—water pressure, traverse speed, and standoff distance—have been chosen. Experiments are conducted using an L9 orthogonal array and investigate how machining parameters affect surface roughness. Percentage contribution of the machining parameters on surface roughness is found using ANOVA. It is observed that the traverse speed has the most significant effects (38.82%) on variations of surface roughness compared to water pressure and standoff distance. The ideal combination of machining parameter values is looked for and experimentally verified. Scanning electron microscopy (SEM) images of the machined surface are also examined.