This paper presents a novel modified electrode for an amperometric hydrazine sensor based on multi-walled carbon nanotubes (MWCNTs) modified with lignosulfonate (LS) and decorated with palladium nanoparticles (NPds). The MWCNT/LS/NPd hybrid was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical properties of the electrode material were evaluated using cyclic voltammetry and chronoamperometry. The results showed that GC/MWCNT/LS/NPd possesses potent electrocatalytic properties towards the electro-oxidation of hydrazine. The electrode demonstrated exceptional electrocatalytic activity coupled with a considerable sensitivity of 0.166 μA μM⁻¹ cm⁻². The response was linear from 3.0 to 100 µM L⁻¹ and 100 to 10,000 µM L⁻¹, and the LOD was quantified to 0.80 µM L⁻¹. The efficacy of the modified electrode as an electrochemical sensor was corroborated in a study of hydrazine determination in water samples.