In this work, a free-standing electrode composed of bismuth terephthalate metal-organic frameworks grown on carbon paper (BiMOF/CP) was successfully prepared by a facile one-pot hydrothermal method. Materials characterization revealed the formation of flower-like ultrathin nanosheets of BiMOF fully covering on the microfibers of carbon paper. The BiMOF/CP was applied in the electrochemical detection of Cd2+ and Pb2+ in water. The BiMOF/CP electrode exhibited superior sensing performance with a linear detection of Cd2+ and Pb2+ with low detection limits of 1.5 μg/L for Cd2+ and 2.7 mg/L for Pb2+, respectively. The significantly enhanced sensing performance compared to bare carbon paper is attributed to the 3D hierarchical architecture of BiMOF and increased number of exposed surface sites, facilitating the adsorption of metals ions and electron transfer. The prepared novel materials will contribute to the development of cost-effective electrochemical sensors for heavy metal detection.