A simple method that combines an electrospray technique with directed assembly using an electrostatic field was used for decorating carbon nanotubes (CNTs) with nanocrystals. Colloidal CdSe and Au nanocrystals were electrosprayed and assembled onto random CNTs and vertically aligned CNTs in a controlled manner. The high level of electrical charge on the electrosprayed aerosol nanocrystals was responsible for the assembly. The technique can be used to assemble various compositions of nanomaterials onto different substrates and provides a versatile route for producing novel hybrid nanostructures.