In this study, a simple, sensitive, and selective colorimetric sensor based on aggregation-induced silver nanoparticles was designed and developed for the determination of spermine. The sensing mechanism relies on electrostatic interactions between the protonated amine groups of spermine and the carboxylate groups of citrate on the surface of silver nanoparticles, leading to nanoparticle aggregation. As a result of this phenomenon, the plasmon peak intensity decreased, a new red-shifted peak appeared at longer wavelengths, and the solution color changed visibly from yellow to purple. The aggregation response of the sensor (A550/A400) exhibited a linear relationship with spermine concentration in the range of 0.2–1.0 µM, with a limit of detection (LOD) of 0.09 µM calculated based on 3Sb/m. Selectivity studies in the presence of other biogenic amines, including spermidine, tryptophan, and histamine, showed negligible interference even at higher concentrations. Moreover, the applicability of the method was validated by determining spermine in extracted chicken meat samples, yielding recoveries of 95–112% with relative standard deviations below 3%. These results indicate that the developed sensor provides a rapid, cost-effective, and efficient approach for monitoring spermine in food samples.