Micro/nanostructured porous ZnO was first utilized as a new binding phase in DGT (diffusive gradients in thin film) devices for selective measurement of Cu(II) in water, on the basis of its selective adsorption performance. In this case, the accumulated heavy metal ions onto the binding phase could be easily determined by a simple complete acid-dissolution elution process without the complicated elution experiments including measurement of elution efficiency. The selective adsorption performance of the micro/nanostructured porous ZnO towards Cu(II) was evaluated in single- and ternary-component metal solutions [Cu(II), Ni(II) and Cd(II) ions]. It was found that the adsorption amount and adsorption rate of Cu(II) ions onto the porous ZnO were the highest by comparing with that of Ni(II) and Cd(II) ions, exhibiting strong adsorption and good selectivity toward Cu(II) ions. The adsorption of heavy metal ions on the ZnO can be well described by Pseudo-second-order model, implying chemical bonding related interaction between the porous ZnO and heavy metal ions. Importantly, the ZnO was utilized as binding phase of DGT device for heavy metal ions measurement, the diffusion coefficient of Cu(II) in the diffusive gel was calculated to be 6.13 × 10−6 cm2 s−1, implying such ZnO could be a new potential binding phase towards trace Cu(II) ions detection.