Significance Methods to stabilize and control magnetic ordering in solids are strongly desired both for fundamental studies and to realize new spintronic technologies. The orientation of ordered magnetic moments is typically set by details of the crystalline environment in which they reside. Here, we report the discovery of a form of magnetic anisotropy which is instead driven by a striking reconfiguration of the underlying fermiology of the system. We show for the oxide material C a 3 R u 2 O 7 how this arises from the interplay of spin–orbit coupling, local polar distortions of the crystal structure, and pronounced electronic correlations. Our findings suggest materials design approaches for manipulating magnetic textures and open pathways to creating large magnetoelectric-type couplings in solids.