Cobalt-based systems provide a unique platform in which strong spin–orbit coupling entangles spin, charge, orbital, and lattice degrees of freedom, leading to pronounced multiferroic behavior. In the present study, magnetic-ordering-enhanced ferroelectricity is observed in flux-grown polar ${\mathrm{Co}}_3{\mathrm{BPO}}_7$ single crystals. Synchrotron x-ray diffraction confirms a noncentrosymmetric polar Cm structure, where ${\mathrm{Co}}^{2+}$ ions form buckled hexagonal layers along the $b$ axis. Magnetic susceptibility and heat-capacity measurements reveal strong anisotropy with two antiferromagnetic transitions at T${}_{\mathrm{N}1}\approx 27\mathrm{K}$ and T${}_{\mathrm{N}2}\approx 15\mathrm{K}$. Neutron diffraction reveals a noncollinear magnetic structure mainly confined to the $ac$ plane, with a finite canting component along the $b$ axis. The three Co ions form a triangular network connected by alternating corner- and edge-sharing units, generating quasihexagonal rings in the $ab$ plane. Dielectric constant, pyroelectric, and second-harmonic-generation measurements show clear magnetoelectric anomalies at both magnetic transitions. Synchrotron x-ray diffraction further identifies local lattice distortions near T${}_{\mathrm{N}1}$, indicating significant magnetoelastic coupling. Berry-phase calculations based on density-functional theory suggest that the absence of inversion symmetry, together with the frustrated triangular Co lattice, stabilizes a noncollinear antiferromagnetic structure. Magnetic ordering enhances spin–spin correlations, activates spin–lattice coupling, and induces a finite Dzyaloshinskii–Moriya interaction, resulting in modulation of the electric polarization.

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• Dielectric properties
• Electric polarization
• Ferroelectricity
• Magnetic anisotropy
• Magnetic phase transitions
• Magneto-dielectric effect
• Pyroelectricity
• Specific heat