The present study explores the impact of Barium (Ba) substitution on the structural, morphological, and magnetic properties of ultrafine Ni1-xBaxFe2O4 (0 ≤ x ≤ 1) nanoparticles synthesized by the cost-effective auto-combustion approach. Structural analysis of synthesized nanoparticles by X-ray diffraction pattern declares the transformation of Fd-3m symmetry to orthorhombic Bb21 m crystal structure. The increasing trend in volume due to the lattice expansion with the addition of Ba in NiFe2O4 is observed. In addition, the crystallite size is reduced from 35.07 to 30.69 nm due to the increase in Ba substitution. The morphology of nanoparticles confirmed by scanning electron microscopy (SEM) determines an increasing trend of grain size from 29 to 36 nm as a function of Ba doping. The room temperature hysteresis loops measured by a vibrating sample magnetometer (VSM) indicate that the magnetic coercivity increases as a function of Ba substitution and provides a maximum value of 3.5 kOe for BaFe2O4. However, saturation magnetization is maximum (∼40.7 emu/g) for NiFe2O4 and declines to a minimum value of ∼26.65 emu/g for BaFe2O4. Moreover, low-temperature magnetic measurements were estimated for BaFe2O4 through physical property measurement system (PPMS), where an increasing trend in coercivity (∼3.2–4.5 kOe), saturation magnetization (∼21–50 emu/g), and effective anisotropic magnetic constant (∼7.06 × 104–2.3 × 105 erg/g) was confirmed as the temperature decreases from 400 to 5 K.