Designing macroscopic, 3D porous conductive materials with high mechanical strength is of great importance in many fields, including energy storage, catalysis, etc. This study reports a novel approach to fabricate polyaniline-coated 3D carbon x-aerogels, a special type of aerogels with mechanically strong, highly cross-linked structure that allows the originally brittle aerogels machinable. This approach is accomplished by introducing a small amount of graphene into the sol-gel process of resorcinol and formaldehyde, followed by physical activation and subsequent cross-linking with polyaniline via electropolymerization. The resulting x-aerogels are not only porous and conductive, but also mechanically robust with high compressibility and fast recovery. The strong combination of these properties makes the x-aerogels promising for high performance supercapacitors that are designed to provide additional functionality for wearable and portable electronics. Such multi-functionality leads to a significant increase in electrochemical performance, in particular high volumetric capacitance, which results from the more densely packed electroactive structure in three dimensions. More importantly, monoliths of carbon x-aerogels are machinable into thin slices without losing their properties, thus enabling effective integration into devices with different sizes and shapes.