Conductive polymer hydrogels (CPHs) have exhibited great potential as advanced material for sensing. Here, a facile approach to 3D networked polypyrrole (PPy) hydrogel is reported. This strategy relies on the doping of the azo dye molecule Tartrazine during the synthesis of nanostructured conductive PPy hydrogel. The prepared PPy hydrogel can be highly dispersible in the mixed solvent of isopropanol/H2O (4/1). The unique 3D network nanostructure endow PPy hydrogels with high electric conductivity and effective interface area for enhanced sensing performance towards the simultaneous determination of ascorbic acid, dopamine and uric acid with respective lower detection limits of 1.283, 0.044 and 0.046 mu mol L-1. The as-designed electrochemical sensor also exhibited excellent stability and reproducibility.