The Cu-I atom in the title complex, [Cu(NH2SO3)(2)(C3H8N)(H2O)], is coordinated by the C=C bond of the allylammonium cation, two N atoms of the sulfamate anions and the O atom of the H2O molecule in the apical position. Thus, the central atom is in a distorted trigonal-pyramidal environment. Strong N-H . . .O and O-H . . .O contacts connect separate moieties of the complex into a three-dimensional framework. The title compound is representative of hitherto unknown copper(I)-sulfamate pi -complexes.