A new paper-based chemiresistive sensor has been developed for the detection of As(III) using a network of single-walled carbon nanotubes (SWCNTs) with electrodeposited gold nanoparticles (AuNPs). The sensor was fabricated using a water-based SWCNT ink by wax printing and vacuum deposition. The sensitivity of the sensor was improved by optimizing the volume of SWCNTs ink used in the formation of the sensing network and the sweep segment of cyclic voltammetry used for the electrochemical deposition of AuNPs. The proposed sensing strategy involves the electrochemical n-doping of As(0) on the AuNPs-SWCNTs channel. The sensor exhibited a low limit of detection of 1.35 × 10-5 μM, which is lower than the maximum permissible concentration in drinking water set by the WHO. The sensing mechanism of the proposed chemiresistive sensor was investigated using a liquid-ion gated FET system. The novel sensing strategy combines the n-doping property of As(0), catalysis of AuNPs on the electrochemical reduction of As(III), p-type semiconducting property of SWCNTs and the flexible, cheap and disposable characteristic of the paper substrate. The sensor showed an enhanced response for different concentrations of As(III) ascribed to the AuNPs-SWCNTs network with a three-dimensional structure formed based on the framework of the paper fibers, which provided an effective electron transfer path and a large specific surface area. The morphological and structural characteristics of the paper-based device confirmed that the AuNPs uniformly covered SWCNTs, and the EDS analysis indicated the successful doping of As(0) on the sensing area, leading to an increase in resistance. The proposed sensing strategy represents an important step towards developing capture probe/receptor-free, ultrasensitive and practical chemiresistive sensors for the detection of As(III) in water. The results of this study offer a simple strategy for developing paperbased chemiresistive sensors with unique properties for practical As(III) determination.