The secret to creating high-performing photothermal catalysts for photocatalytic overall water splitting was the careful design of light absorbers and photogenerated charge transfer pathways. Here, we presented a nonmetallic dual-plasmonic catalyst of MoO3-x/ZrN for photocatalytic H2 and O2 evolution that integrated the localized surface plasmon resonance (LSPR) effect and the S-scheme photogenerated charge transfer route with two different plasma semiconductors. This noble-metal-free catalyst’s dual-plasmonic action demonstrated its potential to tune the long-wavelength photon reflectance (LSPR) absorption spanning the visible to near-infrared (NIR) spectral region and convert photon energy into localized heat. The photogenerated electrons at the conduction band of MoO3-x and the photogenerated holes at the valence band of ZrN were driven to recombine with each other by the inherent electric field in the interface between MoO3-x and ZrN. This allowed the photogenerated holes at the valence band of MoO3-x and the photogenerated electrons at the conduction band of ZrN to be reserved for strong H2 and O2 evolution, respectively. Consequently, MoO3-x/ZrN exhibits remarkable photothermal catalytic performance in overall water splitting. Under light irradiation, the catalyst achieved a H2 and O2 yield rate of 204.22 μmol g−1 h−1 and 95.85 μmol g−1 h−1. This work demonstrated the viability of using two plasma semiconductors to realize wide-spectrum driven photocatalysis by connecting the S-scheme heterojunction and LSPR effect.