Carbon nanobelts have been synthesized using nanoporous anodic alumina as template and ethanol as precursor. The length and width are tens of micrometers and 470 nm, respectively. The thickness was measured to be 5 nm, exhibiting a high-aspect-ratio morphology. After annealing, the crystallinity of the nanobelts can be improved. The formation mechanism of such morphology is demonstrated as a radial deformation of large thin nanotubes. This is disclosed for the first time in the literature regarding the attainment of a quasi two-dimensional nanocarbon via a template route. Field emission measurements on the sample annealed at 800 °C show a turn-on voltage 3.25 V/μm and stable long-term emission efficiency. The lower threshold voltage is attributed to the strong edge emitter effect.