In this paper, we develop a cylindrical triboelectric nanogenerator (TENG) for omnidirectional wind energy harvesting, by designing a slanted slit structure along the outer surface of the cylinder. The TENG consists of an inner cylinder based on Al film and a 3D printed outer structure. Wind blowing through the slits of the outer structure causes the inner cylinder to rotate in the slanted direction, and the contact-separation between the Al cylinder and polytetrafluoroethylene attached to the inner surface of the outer structure generates an output voltage. The performance of the harvester with different inner cylinder diameters under various wind speeds is experimentally studied. The results indicate that the TENG with a smaller Al cylinder is suitable for a self-powered wind speed sensor while that with a larger cylinder is optimal for efficient energy harvesting. In addition, the TENG is capable of harvesting wind energy in all directions. Its potential utility to be used as a supplementary power source for small electronic devices is verified through various experiments. Based on its compact size, simple design, and ease of manufacturing, the proposed TENG can be used as a low-cost, portable harvester.