Graphene-reinforced polylactic acid (PLA-GR) is widely used in structural applications where high compressive strength is required. The present work focuses on optimizing material extrusion process parameters of 3D-printed PLA-GR composites and studying the compression properties of, with a specific emphasis on analyzing different filling patterns. Three infill patterns, namely, linear (L), rectilinear (R), and triangular (T), were examined to assess their influence on the compressive strength of the composite material. During the experimentation procedure, all other parameters were kept constant to ensure a consistent testing environment. The results show that the (L) filling pattern exhibited higher compression strength than the (R) and (T) patterns. Optimization of material extrusion infill patterns is crucial for enhancing the mechanical performance of 3D-printed materials. The optimization of material extrusion infill patterns is an essential step in the process of improving the mechanical performance of materials that have been 3D printed.