A flexible under-nail support device and method to apply the same that promotes long healthy fingernail growth by providing nail strength and support without any interaction or damage to the nail plate (upper nail) or the hyponychium (thickened epidermis under the nail). The device has an indention, with a preferred embodiment of an inverted V that is positioned under the fingernail and around the hyponychium. Its lateral sides are bonded to at least the nails' lateral undersides to provide extra strength to the nail. The bonded device is then clipped and filed to the natural nails length. The method includes healthy easy device removal and support replacement. As the nail grows, the process of attaching and removing supports is repeated and over time results in strong, long, healthy, aesthetically pleasing nails. For immediate nail lengthening, the device may be used as scaffolding with other technologies mitigating their respective health hazards.