The title complex, [Ag3Br2(C25H22P2)3]Br·C7H8N2S, comprises a trinuclear [Ag3Br2(C25H22P2)3]+ unit, a Br− anion and one N,N′-dimethylthiourea molecule (ptu). Three AgI ions are linked via two μ3-bridging Br atoms, leading to a distorted triangular bipyramid with an Ag...Ag separation range of 3.1046 (6)–3.3556 (6) Å. The triangular Ag3 arrangement is stabilized by six P atoms from three chelating bis(diphenylphosphanyl)methane (dppm) ligands. The AgI ion presents a distorted tetrahedral coordination geometry. In the crystal, the bromide anion is connected to the ptu molecule through N—H...Br hydrogen bonds [graph-set motif R21(6)]. Each bromide/ptu aggregate links the complex ion via C—H...S and C—H...Br hydrogen bonds, leading to the formation of a three-dimensional network. Two phenyl rings from two dppm ligands were modelled as disordered over two sites.