With increasing concerns about light pollution and energy waste in general lighting, efficient and effective lighting techniques have become imperative. We present the design of a kind of dedicated oblique illumination (OI) system to solve the problems of light pollution and the waste of energy in general lighting. The OI system consists of an extended (actual) light source, a collimator, and a freeform reflector array. Two different layouts of the OI system are proposed for different lighting situations, and design models of the two layouts are also given by use of the Monge–Ampère equation method. Two typical lighting situations, street lighting and advertising board lighting, are given here to illustrate the proposed OI system, and characteristics of the OI system are explored. The results show the light distribution is well controlled with a pretty good optical performance and the OI system has a large tolerance to the change of intensity distribution of the light source and to the size of the light source.