The work aims to demonstrate a high-performance pH sensor based on tungsten oxide (WO3)/polyaniline (PANI) composites. Both WO3 and PANI were prepared by in-situ polymerization, mixed in solution and spin-coated onto a flexible carbon substrate. The composite was characterized by scanning electron microscopy, Raman spectroscopy, XRD and other techniques to prove the successful synthesis of the composite and further explain its sensing enhancement principle. WO3@PANI could work at pH=2~10, with higher sensitivity (–53.13 mV), lower lag (3.8%) and faster reaction (16 s) compared with the monomeric material. The response remained above 95% after 10 acid-base cycle tests and remained stable during 12 h of continuous testing. On the one hand, PANI provides a conductive network for WO3, and evenly wraps WO3 in it; and on the other hand, the p-n structures of them work together to further improve the pH sensing performance of WO3@PANI.