GaN has emerged, in the past two decades, as one of the most important semiconductors with applications such as solid state lighting and power electronics. Separation and transfer of GaN device layers could produce measureable improvements in light extraction, thermal management, leakage reduction, and strain mitigation. Laser lift-off (LLO) is a relatively established process to separate GaN from sapphire substrates. However, issues such as yield, homogeneity, processing time, and cost make such a process still cumbersome. Lateral undercut etching of GaN has been accomplished with bandgap-selective photoelectrochemical etching in an InGaN/GaN heterostructure, or a conductivity-selective electrochemical etching. A few groups have investigated the growth of sacrificial layers such as AlInN and CrN that are compatible with epitaxial process yet amenable to wet etching. In this work, we present a new scheme in splitting and lifting-off GaN using nanoporous (NP) GaN medium by a simple and robust electrochemical (EC) etching process. This procedure can be considered an implementation of the "smart-cut" principle using nanoscale wet etching and is compatible to wafer-level scaling up. The NP GaN produced by the EC etching offers a new way to selectively weaken the mechanical strength of GaN, making it possible to split and separate epitaxial GaN layer. The use of the nanoetching leads to a flexible process in forming columnar pores during the initial vertical drilling, followed by localized isotropic etching deep in the layer to create lift-off. This procedure can be applied to almost all semiconductors but is especially pertinent to GaN with its given its chemical inertness. We demonstrate that large area (≥1 cm2), free-standing GaN layers, with a thickness from 0.5 to a few microns, can be separated in less than 20 minutes, and the mono-crystallinity of the lift-off GaN layers is well preserved by this process. The substrate was recycled after large area GaN liftoff. Acknowledgement: Yu Zhang would like to express his thanks to Dr. Zhenting Jiang for help with Raman measurement.