The present study has investigated the synthesis of silver nanoparticles (AgNPs) using starch as a biodegradable reducing/stabilizing agent with the assistance of microwave heating and light-emitting diode (LED) irradiation. The presence of microwave and LED irradiation enhanced the formation rate of AgNPs. Silver nanoparticles treated with blue LED (AgNPs-L) were produced at a starch concentration of 25 g/L under blue LED treatment for 120 min, while a starch concentration of 25 g/L, the power level of 110 W, and heating time of 5 min were found optimal conditions for silver nanoparticles treated with microwave (AgNPs-M) formation. The synthesized AgNPs-M possessed a sharp absorption peak at a maximum wavelength of 401 nm and spherical with an average size of 19.8 nm. Although a larger particle of 27.8 nm corresponded to a maximum absorption wavelength at 446 nm, AgNPs-L exhibited better antimicrobial activity against Gram-negative bacteria (S. aureus, B. subtilis, and L. fermentum), Gram-positive bacteria (S. enterica, E. coli, and P. aeruginosa), and fungus (C. albicans).