In this Letter, a light management structure composed of wedge-shaped semiconductor nanowall arrays is introduced. Theoretical investigation based on gallium arsenide (GaAs) indicates that a 1000 nm high array (wall base width/array periodicity: 500 nm) with an effective thickness of only 500 nm can deliver a maximum photocurrent density (Jph) of ∼29.0 mA/cm2 at AM1.5G illumination. (For an ideal absorber with the same bandgap, the corresponding value is ∼32.0 mA/cm2.) However, Jph of a 1500 nm thick flat GaAs film is only ∼19.2 mA/cm2 at the same illumination condition. The wedge-shaped nanowall arrays meanwhile exhibit good omnidirectional light confinement. At the incident angle of 60°, Jph of the aforementioned nanowall array is ∼12.7 mA/cm2, and the corresponding value for an ideal absorber is ∼16.0 mA/cm2. Considering the simple structure and excellent light confinement in a broad range of the system parameters, including array periodicity, the nanowall height, and the incident angle of light, the wedge-shaped semiconductor nanowall arrays provide a valuable platform for fabricating the related high performance-to-cost semiconductor optoelectronic devices.