The photocatalytic performance of the g-C₃N₄ photocatalyst was restricted by the low efficiency because of the fast charge recombination. The present work constructed a “killing two birds with one stone” composite (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂/g-C₃N₄ heterostructured photocatalysts with the aim to greatly promote the charge separation and recycle decatungstate in aqueous solution. Decatungstate was immobilized on g-C₃N₄ in the form of modified decatungstate (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂ via surface bonding method for the first time. Furthermore, a novel ternary (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂/g-C₃N₄/rGO photocatalyst was successfully constructed by integrating graphene into the binary (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂/g-C₃N₄ composite as the electron mediator. The photocatalysts were characterized by XRD, FTIR, FESEM, TEM, UV-vis DRS, PL and EIS measurement. The photocatalytic properties were evaluated in photodecomposition of aqueous methyl orange and phenol under visible-light irradiations. It has been shown that the obtained (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂/g-C₃N₄ photocatalyst exhibited improved photocatalytic activity and enhanced reduced charge recombination as compared with those of g-C₃N₄ and (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂. It has been found that the introduction of graphene revealed a synergistic effect between the (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂ species, g-C₃N₄ and graphene existed in the ternary photocatalyst. Consequently, the photocatalytic activity of the ternary (C₁₆H₃₃(CH₃)₃N)₄W₁₀O₃₂/g-C₃N₄/rGO photocatalyst was superior to that of the binary one, originating from its stronger visible-light absorption and more reduced charge combination. Finally, recycling experiments revealed that the ternary composite photocatalyst was not only highly efficient but also robust, because it can be used six times without loss of activity, which efficiently solved the problem of recycling decatungstate in reaction system. This work demonstrated that rational design and construction of g-C₃N₄-decatungstate composites could open up a new avenue for the development of new efficient visible-light photocatalysts for water disinfection.