Barium imidonitridophosphate BaP6N10NH was synthesized at 5 GPa and 1000 °C with a high‐pressure high‐temperature approach using the multianvil technique. Ba(N3)2, P3N5 and NH4Cl were used as starting materials, applying a combination of azide and mineralizer routes. The structure elucidation of BaP6N10NH (P63, a=7.5633(11), c=8.512(2) Å, Z=2) was performed by a combination of transmission electron microscopy and single‐crystal diffraction with microfocused synchrotron radiation. Phase purity was verified by Rietveld refinement. 1H and 31P solid‐state NMR and FTIR spectroscopy are consistent with the structure model. The chemical composition was confirmed by energy‐dispersive X‐ray spectroscopy and CHNS analyses. Eu2+‐doped samples of BaP6N10NH show blue emission upon excitation with UV to blue light (λem=460 nm, fwhm=2423 cm−1) representing unprecedented Eu2+‐luminescence of an imidonitride.