In this study, we report a high In composition {11-22} InGaN underlayer grown on an m-plane sapphire substrate and the multi-quantum wells (MQWs) grown on it. The InGaN template with high In composition (In:~18%) was fully relaxed. The MQWs photoluminescence (PL) spectrum on the InGaN underlayer exhibited a higher emission intensity and a longer emission wavelength compared with that on a GaN template. Additionally, when the InGaN underlayer was adopted, an InGaN barrier was more suitable than a GaN barrier for the long-wavelength (red) region; the PL spectrum of InGaN/InGaN MQWs was twice as high as that of InGaN/GaN MQWs in the red emission region. Finally, we investigated the optical polarization of the MQWs on {11-22} InGaN underlayers and discussed its characteristics using theoretical equations.