Novel multifunctional Ba 5 Zn 4 Y 8 O 21 :Tb 3+ nanorods, fabricated via solution combustion route, have been found to go in the tetragonal system with the I4/m (87) crystallographic space group. The diffuse reflectance (DR) studies unveiled a band-gap of 3.77 eV for Ba 5 Zn 4 Y 7.84 Tb 0.16 O 21 (most emitting composition). The ultra-violet (UV) excitation at a wavelength of 290 nm for all Ba 5 Zn 4 Y 8 O 21 :Tb 3+ samples produced the characteristics emission peaks corresponding to 5 D 4  →  7 F 6,5,4,3 transitions in Tb 3+ (used to obtain Judd–Ofelt parameters). The critical distance of energy transfer between neighboring Tb 3+ ions was found to be 18.62 Å, and helped to shortlist the right mechanism responsible concentration quenching phenomena (dipole–quadrupole). The in-depth analysis of photoluminescence (PL) decay curves and emission spectra of Ba 5 Zn 4 Y 8 O 21 :Tb 3+ nanorods delivered the value of radiative lifetime (1.1934 ms) and total radiative rates from 5 D 4 state in Tb 3+ . The radiative probabilities of electric-dipole transitions (extracted from total radiative rates i.e. magnetic-dipole + electric-dipole) were used to calculate the Judd–Ofelt intensity parameters (Ω 2  = 3.98 × 10 −20 , Ω 4  = 1.76 × 10 −20 and Ω 6  = 0.28 × 10 −20 cm 2 ). The quantum efficiency of 5 D 4 state in Ba 5 Zn 4 Y 7.84 Tb 0.16 O 21 phosphor was calculated to be 79% with pure green emission, signifying their potential use in display and lighting devices. As a final point, the high magnitude of emission cross-section of 5 D 4  →  7 F 5 (14.84 × 10 −20 cm 2 ) transition also claims their promising candidature as a good laser crystal.