Global demand for green and clean energy is increasing day by day owing to ongoing developments by the human race that are changing the face of the earth at a rate faster than ever. Exploring alternative sources of energy to replace fossil fuel consumption has become even more vital to control the growing concentration of CO2, and reduction of CO2 into CO or other useful hydrocarbons (e.g., C1 and C≥2 products), as well as reduction of N2 into ammonia, can greatly help in this regard. Various materials have been developed for the reduction of CO2 and N2. The introduction of pores in these materials by porosity engineering has been demonstrated to be highly effective in increasing the efficiency of the involved redox reactions, over 40% increment for CO2 reduction to date, by providing an increased number of exposed facets, kinks, edges, and catalytically active sites of catalysts. By shaping the surface porous structure, the selectivity of the redox reaction can also be enhanced. In order to better understand this area benefiting rational design for future solutions, this review systematically summarizes and constructively discusses the porosity engineering in catalytic materials, including various synthesis methods, characterization of porous materials, and the effects of porosity on performance of CO2 reduction and N2 reduction.