We experimentally investigated the electrical and electromagnetic (EM) properties of pyrolytic carbon (PyC) ultrathin films synthesized on a quartz substrate by chemical vapor deposition at 1100°C using low pressure gas mixture as carbon source. PyC films consist of randomly oriented and intertwined graphene ribbons, which have a typical size of a few nanometers. We discovered that the manufactured PyC films of 35-nm thickness provided remarkably high attenuation caused by absorption of 37% to 24% of incident microwave power. The temperature dependence of PyC’s direct-current (DC) conductivity represents typical behavior for disordered systems. Being semitransparent in visible and infrared spectral range and highly conductive at room temperature, PyC films emerge as a promising material for manufacturing ultrathin microwave (e.g., band) coatings to be used in aerospace applications.