Microinjection molding (µIM) is an important technology for fabricating micro-moldings (µ-moldings) used in various applications, such as microelectromechanical systems (MEMS) and other microsystems. Compared with conventional injection or compression molding processes, µIM involves higher thermal gradients, higher shear rates and shorter cycle times. The properties of µ-moldings are affected significantly by the molding conditions and materials employed. Presently, there is a trend towards manufacturing multifunctional components which could fulfill multiple-tasks simultaneously. Therefore, µIM of filler loaded polymer nanocomposites is receiving research attention. In this study, a series of polypropylene (PP) nanocomposites loaded with different carbon fillers, i.e. carbon nanotubes (CNT), carbon black (CB) and graphite nanoplatelets (GNP), were prepared by melt blending, followed by compression molding or µIM. Direct current electrical conductivity and melt rheology measurements were utilized to probe the percolated structure of the compression molded PP/carbon nanocomposites. For µIM, a mold insert which has a three-step decrease in thickness along the flow direction was adopted to study the effect of abrupt changes in mold geometry on the electrical and morphological properties of the µ-moldings. To facilitate characterization, the µ-moldings were mechanically sectioned into three different sections based on part thickness. Results indicated that the µ-moldings exhibited higher percolation thresholds when compared with their compression molded counterparts. This could be ascribed to the severe shearing conditions that are present in µIM. The morphology of the µ-moldings containing different carbon fillers was examined using scanning electron microscopy (SEM) for each cut section. The development of corresponding microstructure was found to be strongly dependent on the type of carbon filler used in µIM, which is critical for the enhancement of electrical conductivity of the µ-moldings.