Transparent zinc-tellurite glasses co-doped with Terbium ion (Tb3+) and Ytterbium ion (Yb3+) were successfully created using the melt-quench method in an air environment. Systematic investigations were conducted using X-ray diffraction, differential scanning calorimeter, UV-Visible-IR, and upconversion spectra to examine the structural, thermal, and optical properties. The absorption peaks from the Tb3+ transitions are located at 486 nm (7F6 / 5D4 ) in the Tb3+ single doped glass. The overlapping absorption bands are believed to be the result of the transition from 5D0 to 3H7 excited-state levels were observed. Under 978 nm laser stimulation, a zinc tellurite glass sample containing Tb3+ and Yb3+ ions showed strong, typical Tb3+ emissions (5D4 - 7F3-6 and 5D3 - 7F4-6). The upconversion’s laser power dependence demonstrated that the two-photon process was in charge of the green emission.