We report on the improvement of the structural and optical properties of m-plane GaN layers on m-plane sapphire via epitaxial lateral overgrowth (ELO) using hydride vapor phase epitaxy. The planar m-plane GaN was compared to ELO mplane GaN with stripes patterned along the [1120] and [0001], respectively. The ELO m-plane GaN samples showed narrow x-ray rocking curves and more improved cathodoluminescence (CL) images compared with those of the planar m-plane GaN. The density of threading dislocations (TDs) and basal-plane stacking faults (BSFs) was decreased in the ELO m-plane GaN, which was confirmed by transmission electron microscopy (TEM) and Williamson-Hall (WH) plot analysis.