The development of energy-sustainable and energy-efficient economy depends on the ability to produce low-cost high-performance renewable materials for electrical energy storage devices. The electrical double layer capacitors (EDLCs) with nanostructured activated carbon (AC) electrodes from natural precursors have attracted considerable attention due to their great cycle stability, combined with moderate cost and attractive overall performance. Such ACs offer high specific surface area, high electrical conductivity, relatively low price, easy and environmental friendly production in large quantities. The recent developments in the synthesis of such AC materials allow for the greatly enhanced specific capacitance in a wide range of electrolytes. This review provides a summary of a recent research progress in synthesis and understanding the critical structure-property relationships for nanostructured ACs and highlights the trends for the future developments of ACs for EDLC applications.