We present the synthesis of the three‐dimensional coordination polymer 3∞[Bi2Br6(tcpt)] [tcpt = 1,3,5‐tris(4‐cyanophenyl)triazine] that could be obtained from a solvent‐free melt synthesis of BiBr3 and 1,4‐dicyanobenzene (dcb). The reaction is based on a quantitative in‐situ formation of the ligand 1,3,5‐tris(4‐cyanophenyl)triazine by trimerization of the dicyanobenzene, and, to the best of our knowledge, is the first Bi‐containing coordination polymer constructed from Bi–nitrile bonds. The framework further exhibits some π stacking of the tcpt ligands. 3∞[Bi2Br6(tcpt)] exhibits green photoluminescence arising from broad banded excitation and emission bands. Furthermore, a photochromic shift of the emission can be observed depending on the excitation wavelength.