A facile and rapid photochemical method to prepare supported silver nanoparticles (Ag-NPs) in a suspension of faujasite-type (FAU) zeolite nanocrystals is described. Silver cations are introduced by ion exchange in the zeolite and subsequently irradiated with a Xe-Hg lamp (200 W) in the presence of a photoactive reducing agent (2-hydroxy-2-methylpropiophenone). UV-Vis characterization indicates that irradiation time and intensity (I0) influence significantly the amount of silver cations reduced. The full reduction of silver cations takes place after irradiation (I0 = 100 % for 60 s), and a plasmon band of Ag-NPs appears at 380 nm. Transmission electron microscopy (TEM) combined with theoretical calculation of the plasmon absorbance band using Mie Theory shows that the Ag-NPs, stabilized in the micropores and on the external surface of the FAU zeolite nanocrystals, have almost a spheroidal shape with diameters of 0.75 and 1.12 nm, respectively. Ag-NPs, with a homogeneous distribution of size and morphology, embedded in a suspension of FAU zeolite are very stable (ca. 8 months), even without any stabilizers or capping agents.