Amine functionalised and consequently cationic linear polymers, Newkome-type dendrons and PAMAM dendrimers can efficiently form electrostatic complexes with negatively charged cowpea chlorotic mottle viruses (CCMVs). The complexes have been characterised by dynamic light scattering (DLS), gel electrophoresis, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), which describe in detail how the size and structure topology of the polyamine controls the complex formation with the virus. DLS results show that the complexes are approximately 1–2 µm in diameter, and their size can be tuned with the charge valency of the polymer and the ionic concentration of the media. TEM images and SAXS measurements demonstrate that individual virus particles can adopt hexagonal close packing within the complex and the observed distance between lattice points (27.9 nm) corresponds to the diameter of the native virus, which is 28 nm. Also the empty viral capsids and capsids loaded with Prussian blue nanoparticles can be assembled, which suggests that by controlling the assembly of the virus, it is possible to control the assembly of any material that is held inside the virus.