The electrostatic discharge (ESD) performance of GaN-based light-emitting diodes (LEDs) with naturally-textured p-GaN contact layers grown on c-axis miscut sapphire substrates are studied. During machine model tests, the device grown on a 0.35° miscut sapphire shows the highest ESD tolerance, while the one grown on a 0.2° miscut sapphire exhibits the poorest tolerance. It is discovered that this effect correlates with the presence of maximum capacitance (Cm) values, over the difference in defect densities between LEDs. The variation in Cm values is caused by parasitic capacitance effect induced by different p-GaN surface morphologies between the studied devices. This observation gives us more reliable application in improving ESD performance based on the device grown on a 0.35° miscut sapphire.