The role of a prominent photonic bandgap (PBG) in the phenomenon of transverse localization of light in a semi-infinite lossless waveguide lattice consisting of evanescently coupled disordered one-dimensional optical waveguides has been investigated numerically. The interplay between the underlying photonic bandgap due to inherent periodicity of the optical system and various levels of deliberately induced transverse disorder in its refractive index periodicity has been studied. We show that the PBG indeed plays an important role and that its simultaneous presence could catalyze realization of localized light even when the strength of disorder is not sufficiently strong to independently cause localization of light. An important outcome of this study revealed that the PBG could be gainfully exploited to tailor the spectral window for localization of light in potential applications such as lasing in a disordered optical lattice. © 2014 Astro Ltd.