Synthesis of well-dispersed gold and silver nanoparticles of various size and shapes was achieved at 30°C by callus and flower extracts of Michelia champaca L. Particularly, gold nanoparticles synthesis by callus extracts was considerably more at 65°C, having a greater diversity in the geometry and size of nanoparticles. The nanoparticles were characterized by several physico-chemical techniques - UV-visible spectroscopy, TEM, EDX, FT-IR, zeta potential, and DLS measurements. The callus-generated gold and silver nanoparticles exhibit a greater diversity in size and shape than the flower extract-generated particles. Nanoparticles capped by the functional groups of the phytochemicals in the callus extract could exhibit greater stability. The synthesized AgNPs also showed competence to degrade methylene blue and exhibited anti-bacterial activity against E.coli DH5α. TLC and GCMS analysis resulted in the detection of lignans and triterpenes in the callus extract. The results have demonstrated that callus cultures of Michelia champaca can serve as novel, renewable bio-resources for controlled synthesis of biocompatible nanoparticles. Copyright © 2016 American Scientific Publishers All rights reserved.