•Dy3+-activated new BaYAlZn3O7 nanopowders have been fabricated via an energy and time saving solution combustion route.•Rietveld refinement technique disclosed their phase-purity and intrinsic crystal framework.•In-depth down-conversion photoluminescence and the effectual energy-relocation has been thoroughly scrutinized.•Potential candidate for cool-WLEDs, digital-signs, horticulture, bio-imaging, solar-cells and lasers. Display omitted Ongoing progress of solid-state illumination technology necessitates the compelling need for energy-efficient nanophosphors with superfine luminance. The present paper reports the synthesis and characterization of nano-crystalline phosphors by incursion of Dy3+ ions into BaYAlZn3O7 matrix. Rietveld-refinement of XRPD profiles revealed the hexagonal structure of as synthesized nano-crystalline phosphors. Non-uniform agglomerated particles with size ranging between 44 and 65 nm have been observed from morphological investigation. The observed white light in the studied nanophosphors is due to emissions lying in blue and yellow domains radiated from 4F9/2 to 6H15/2, 13/2 states of Dy3+ respectively. Inokuti-Hirayama (I-H) and Dexter’s models have been employed to understand the phenomenon of Photoluminescence. It has been observed that d-d (dipole-dipole) inter-linkages chiefly command the luminance-quenching for nanophosphor with Dy3+ content (x) equal to 0.05. Various radiative-possessions reflecting better luminance-potentiality of presently studied nanophosphor like decay-time, intrinsic life-time, quantum-efficiency and relaxation-rate have also been evaluated. White light parameters viz. CP and CCT values of BaY0.95Dy0.05AlZn3O7phosphors are 19.84 × 10−2 and 8088.31 K, respectively along with CIE-1931 coordinates (x = 0.2588, y = 0.3306), imply the studied nanophosphor to be a new superfine cool-white-emanating material for nUV-activated WLEDs (white-light-emanating diodes), portable-electronics, signage, aircraft-cabins, digital communication, sensors, horticulture, solar-cells and advanced lasers. The reported outcomes will certainly open an avenue for researchers to design more BaYAlZn3O7-like materials.