•Zeolitic imidazolate frameworks (ZIFs) with different dimensions were synthesized.•The electrochemical performance of ZIFs is dimensional-dependent.•One-dimensional ZIF performs best owing to the morphological and textural merits. So far, direct utilization of zeolitic imidazolate frameworks (ZIFs) as the electrode materials for high-performance supercapacitors (SCs) is challenging owing to their poor electrochemical performance. However, for the first time, the electrochemical activities of ZIFs are found to be dimensional dependent in this study, and can be greatly boosted by reducing the dimension from three-dimension (3D) or two-dimension (2D) to one-dimension (1D). The unique 1D architecture endows 1D ZIF with improved conductivity as well as a high surface-to-volume ratio to facilitate the accessibility of electrolyte ions. Additionally, 1D ZIF is highly defective with abundant linker-missing defects, leading to the favorable exposure of cobalt ions as the redox active sites responsible for pseudocapacitance. Benefiting from these structural and textural merits, 1D ZIF exhibits a much higher charge storage capacity, rate capability and cycling stability than 2D and 3D ZIF. When assembled with activated carbon (AC), the asymmetric supercapacitor device (1D ZIF//AC) can deliver an impressive energy density of 76 Wh kg−1 at a power density of 800 W kg−1, superior to many other ZIFs, ZIF-based composites, ZIF-derived carbon, and even some advanced metal compounds reported in literature. Display omitted