The first electrochemical immunosensor for the determination of CXCL7 (chemokine (C-X-C motif) ligand 7) autoimmune biomarker is reported in this work. Click chemistry-assisted antibodies immobilization was performed by reaction of azide functionalized-multi-walled carbon nanotubes (MWCNTs) and ethynyl-IgG onto screen-printed carbon electrodes. The capture antibodies were further immobilized onto IgG-MWCNTs conjugates. After a blocking step with casein, a sandwich immunoassay was implemented involving biotinylated detector antibodies and alkaline phosphatase (AP)-streptavidin conjugate. Differential pulse voltammetry upon addition of 1-naphthylphosphate was used as the analytical readout. A linear calibration plot between 0.5 and 600 pg mL(-1) CXCL7 and a LOD value of 0.1 pg mL(-1) were obtained. The usefulness of the immunosensor was demonstrated by the successful analysis of serum samples from patients with rheumatoid arthritis.