Pure and Co3+-doped BaAl2O4[Ba(Al1–xCox)2O4, x= 0, 0.0077, 0.0379] powder samples were prepared by a facile hydrothermal route. Elemental analyses by static secondary ion mass spectrometry (SIMS), X-ray absorption spectroscopy (XAS) measurements at the Co K-edge, and X-ray diffraction studies were fully correlated, thus addressing a complete description of the structural complexity of Co3+-doped BaAl2O4powder. Powder X-ray diffraction (PXRD) patterns indicated that prepared samples were nanocrystalline with a hexagonal P63symmetry. The X-ray absorption near-edge structure (XANES) measurements revealed the presence of cobalt in a +3 oxidation state, while the rarely documented, tetrahedral symmetry around Co3+was extracted from the extended X-ray absorption fine structure (EXAFS) oscillation patterns. Rietveld structure refinements showed that Co3+preferentially substitutes Al3+at tetrahedral Al3 sites of the BaAl2O4host lattice, whereas the (Al3)O4tetrahedra remain rather regular with Co3+–O distances ranging from 1.73(9) to 1.74(9) Å. The underlying magneto-structural features were unraveled through axial and rhombic zero-field splitting (ZFS) terms. The increased substitution of Al3+by Co3+at Al3 sites leads to an increase of the axial ZFS terms in Co3+-doped BaAl2O4powder from 10.8 to 26.3 K, whereas the rhombic ZFS parameters across the series change in the range from 2.7 to 10.4 K, showing a considerable increase of anisotropy together with the values of the anisotropic g-tensor components flowing from 1.7 to 2.5. We defined the line between the Co3+doping limit and influenced magneto-structural characteristics, thus enabling the design of strategy to control the ZFS terms’ contributions to magnetic anisotropy within Co3+-doped BaAl2O4powder.