Herein, we report, for the first time, the influence of the state of spin of the Cr3+ ions on the structure and magnetic behavior of LaFe1−xCrxO3 (0.0 < x < 0.5) perovskite crystal structures to improve their magnetic properties for memory storage and magneto-optical application potential. A series of LaFe1−xCrxO3 (0.0 < x < 0.5) nanocrystals was prepared using the citrate-nitrate auto-combustion route. The influence of the Cr3+ ions on the structure and morphology of the LaFe1−xCrxO3 nanostructures was emphasized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), the selected area of electron diffraction (SAED), and scanning electron microscopy (SEM). The results revealed that the inclusion of the Cr3+ ions into the Fe3+ sites leads to an increase in the crystallite size of the LaFe1−xCrxO3 (0.0 < x < 0.5) nanocrystals, from 16.12 to 57.29 nm, to preserve their orthorhombic crystal symmetry. The phase stability and the electron density mapping of the prepared orthoferrite nanocrystals were verified using the Goldschmidt tolerance factor and Rietveld refinement. The magnetic properties were evaluated and discussed based on Kanamori–Goodenough (KG) regulations and Heisenberg Hamiltonian notation. The results showed that the inclusion of the 20 mol% of Cr3+ ions in the Fe sites results in an enhancement of the magnetic parameters. The enhancement of the magnetic behavior was argued to the tendency of the Cr3+ ions to be in the high spin state when included in the Fe3+ ions site. This improvement in the magnetic performance of the LaFe1−xCrxO3 (x = 0.2) nanocrystals will open a new avenue for using this nanomagnetic material in the fields of memory storage and magneto-optical devices.