We report here a method to integrate discrete multicomponent assembly into molecular electronic devices. We first functionalize a molecule wired between the ends of a single-walled carbon nanotube so that it can be derivatized with a probe molecule. This probe then binds to a complementary biomolecule to form a noncovalent complex. Each step of chemical functionalization and biological assembly can be detected electrically at the single event level. Through this combination of programmed chemical reactions and molecular recognition, we are able to create complex multimeric nanostructures incorporating isolated metallic nanoparticles.