The title complex, [RhBr(C8H12)(C19H22N2O2)], has a distorted square-planar geometry. There are two molecules, A and B, in the asymmetric unit. The Rh-C bond distance between the N-heterocyclic ligand and the metal atom is 2.039 (2) A in molecule A and 2.042 (2) A in molecule B. The angle between the carbene heterocycle and the coordination plane is 87.56 (12) degrees in molecule A and 87.03 (11) degrees in molecule B. It is shown that the average Rh-C(COD) (COD is cyclooctadiene) distance is linearly dependent on the Rh-C(imidazolidine) distance in this type of compound. This can be ascribed to the steric hindrance produced by the packing. The crystal structure contains intramolecular C-H...O and intermolecular C-H...Br interactions.