Much research has been devoted to the incorporation of erbium (Er) into semiconductors aimed at achieving photonic integrated circuits with multiple functionalities. GaN appears to be an excellent host material for Er ions due to its structural and thermal stability. Er-doped GaN (GaN:Er) epilayers were grown on different templates, GaN/Al2O3, AlN/Al2O3, GaN/Si (111), and c-GaN bulk. The effects of stress on 1.54 μm emission intensity, caused by lattice mismatch between the GaN:Er epilayer and the substrate, were probed. The emission intensity at 1.54 μm increased with greater tensile stress in the c-direction of the GaN:Er epilayers. These results indicate that the characteristics of photonic devices based on GaN:Er can be optimized through strain engineering.