Silver manganese oxide (AMO) nanoparticles (Nnp) were synthesized using the co-precipitation method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), (EDS) to confirm their structural and morphological properties. The synthesized AMO was incorporated with multi-walled carbon nanotubes (MWCNTs) to fabricate a modified glassy carbon electrode (GCE). This AMO-MWCNT Nnp composite electrode demonstrated remarkable efficiency for the simultaneous electrochemical detection of norepinephrine (NEP), uric acid (URA), and L-tyrosine (L-TY). Employing cyclic voltammetry (CV) and differential pulse voltammetry (DPV), the sensor exhibited excellent sensitivity and selectivity. Under optimal conditions, DPV was used for the simultaneous detection of NEP, URA, and L-TY at AMO Nnp-modified surfaces, achieving low detection limits of 4.04 nM for NEP, 3.01 nM for URA, and 10.31 nM for L-tyrosine. The synergistic effect of AMO Nnp and MWCNTs enhanced electron transfer kinetics, ensuring precise multi-analyte quantification. This work highlights the potential of the AMO-MWCNT Nnp modified electrode as a vigorous platform for advanced biomolecular sensing applications and real sample analysis.