In this report, gold nanoparticle–graphene nanohybrids (Au–GR) and 3-amino-5-mercapto-1,2,4-triazole-functionalized multiwall carbon nanotubes (MWCNT–SH) were synthesized. And a novel hybrid material MWCNT–SH@Au–GR was obtained by the interaction between gold nanoparticles of two dimensional (2D) Au–GR and SH groups of 1D MWCNT–SH. Due to the synergistic effects between MWCNT–SH and Au–GR and excellent film forming ability of MWCNT–SH@Au–GR, the obtained MWCNT–SH@Au–GR was used as a modifier to fabricate a chemically modified electrode for the simultaneous determination of hydroquinone (HQ), catechol (CC), resorcinol (RC) and nitrite (NO₂⁻). Scanning electron microscopy (SEM) was employed to characterize the morphology of MWCNT–SH@Au–GR. The electrochemical behavior of the sensor was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Results showed that it was feasible to simultaneously measure HQ, CC, RC and NO₂⁻. The linear response ranges for HQ, CC, RC and NO₂⁻ were 54.5–1250.5 μM, 11.0–126.0 μM, 43.5–778.5 μM and 86.0–7500.0 μM and the detection limits (S/N = 3) were 4.17 μM, 1.00 μM, 7.80 μM and 23.5 μM, respectively.