The sol-gel auto-combustion (SC) procedure was utilised to fabricate lanthanum-doped Mg-Zn nanostructures with the chemical composition, Mg0.6Zn0.4LaxFe2-xO4, (x = 0, 0.05, 0.10). X-ray diffraction showed nanocrystalline and single-phase of Mg-Zn nanostructures. The morphological traits showed formation of irregular and aggregated grains. Fourier transform infrared spectroscopy detected the formation of two characteristic band positions that fall within the range of 400 to 600 cm−1 and may occur because of stretching vibration within metal-oxygen (M-O) cations located at interstitial positions. From the M-H loops, the excellent values of magnetic factors, such as the saturation magnetization (Ms), rentivity (Mr), and coercivity (Hc) ranging from 35.30 to 44.79 emu g−1, 1.40 to 3.75 emu g−1, and 11.56 to 41.42 Oe were obtained. The loss tangent (tan δ) was observed to be miniscule for all of the samples due to which they can be useful for electronic applications. However, the initial values of the real permeability (
μ
′
) was high and it decreases until 4 GHz, after which it acquires a constant value for rest of frequency range. However, observed low values of the magnetic loss tangent (tan δ
μ
) were due to the large grain size and the high densification of the samples.