<p>Double perovskite oxides with the general formula A₂BB’O₆ are widely recognized for their rich multifunctionality arising from strong spin–charge–lattice coupling. In this work, we present the successful synthesis and comprehensive characterization of Dy₂NiFeO_6−δ, a cobalt-free double perovskite oxide, via a wet chemical sol–gel route. X-ray diffraction (XRD) patterns validate the formation of a monoclinic <i>P2₁/n</i> structure with lattice parameters (<i>a</i> = 5.396 Å, <i>b</i> = 5.635 Å, <i>c</i> = 7.4873 Å, β = 90.285°). Transmission electron microscopy (TEM) reveals agglomerated nanocrystalline particles,&#xa0;where agglomeration originates from high surface energy, and magnetic dipole–dipole interactions may further enhance clustering. X-ray photoelectron spectroscopy (XPS) confirms the presence of Dy³⁺, Ni²⁺, and Fe²⁺ oxidation states, indicating oxygen deficiency (δ ≈ 0.5). Dielectric measurements demonstrate a frequency-dependent decline in permittivity (10&#xa0;Hz–5&#xa0;MHz) due to interfacial polarization, while temperature-dependent studies (298–523&#xa0;K) exhibit an increase in dielectric constant, associated with thermally activated dipolar alignment and relaxation behavior in dielectric loss. AC conductivity increases with increasing temperature, indicating a negative temperature coefficient of resistance and a charge transport mechanism dominated by hopping conduction with an activation energy of 0.16&#xa0;eV. Magnetic studies reveal a Néel temperature of ~ 107&#xa0;K, with features of weak ferromagnetism and a spin-glass-like transition emerging below ~ 50&#xa0;K, driven by 4f–3d exchange interactions and spin canting. The interrelationship between structural, dielectric, and magnetic properties underscores the multifunctional nature of Dy₂NiFeO_6−δ. While direct magnetodielectric or magnetoelectric coupling measurements remain to be explored, the observed multifunctional behavior suggests that this material shows promise for future magnetoelectric and spintronic applications.</p>