Er 3+ doped boro-tellurite glasses have been prepared by the conventional melt quenching technique with the chemical composition (39−x) B 2 O 3 +30TeO 2 +15MgO+15K 2 O+xEr 2 O 3 (where x=0.01, 0.1, 1, 2 and 3wt%). The structural analysis of the glasses were made through XRD, FTIR spectral measurements and the optical absorption, luminescence measurements were made to analyze the optical behavior of the prepared glasses. The bonding parameters were determined from the optical absorption spectra and were found to be ionic in nature. The experimental oscillator strengths were determined from the absorption spectra have been used to determine the Judd–Ofelt parameters. The Judd−Ofelt parameters were used to explore the important radiative parameters such as transition probability (A), stimulated emission cross-section (σ P E ) and branching ratios (β R ) of the emission transitions 2 H 9/2 → 4 I 15/2 and 2 H 11/2 and 4 S 3/2 → 4 I 15/2 of the trivalent erbium ions. The optical band gap energy (E opt ) values corresponding to the direct and indirect allowed transitions and the Urbach energy values of the prepared Er 3+ doped boro-tellurite glasses have been calculated and discussed with similar studies. The spectroscopic behavior of the Er 3+ boro-tellurite glasses have been studied by varying the trivalent erbium ion content and the results were discussed and compared with similar studies.