We investigated the effect of double air gaps embedded between sapphire and undoped GaN on the strain reduction in the InGaN/GaN-based green LED structure. Selective GaN growth and electrochemical etching were exploited to achieve embedded air gaps. Raman spectroscopy and photoluminescence were employed to demonstrate the relation between strain relaxation and indium incorporation. The double air gaps caused strain relaxation and led to a higher In incorporation in InGaN layers, which in turn caused a redshift of the PL spectra. As a result, three different peak wavelengths according to the existence of air gaps were observed.