Here, we fabricate an ultrasensitive acetaminophen (AC) sensor by using networked nanocarbons (NWNC) derived from hierarchical porous polypyrrole (PPy) hydrogel precursor. Benefiting from the interconnected porous framework and high electron conductivity of this N, P co-doped NWNC, the as-constructed sensor shows record-high sensitivity (102.05 mu A mu M-1 cm(-2)) and ultra-low detection limit (3.0 nM), which represents a performance progress in AC sensing. Furthermore, the sensor displays excellent selectivity, reproducibility and stability, exhibiting a great perspective in ultrasensitive monitoring of AC in clinical application. (c) 2018 The Electrochemical Society.