The aim of this paper is to study the effect of heat-treated silver NPs on the up-converted luminescence of Dy3+-doped tellurite glass. Therefore, in the current study, Dy3+-doped lead–sodium–tellurite glasses containing silver NPs are prepared by a conventional melt-quenching technique and subsequent heat-treatments at near the glass transition temperature. Furthermore, the samples are characterized using the X-ray diffractometry (XRD) technique, UV–vis-IR absorption spectroscopy, photoluminescence spectroscopy (PL), transmission electron microscopy (TEM) and the selected-area electron diffraction (SAED) technique.