Ferritin cage nanoparticles are promising platforms for targeted delivery of imaging and therapeutic agents. One of the main advantages of cage nanoparticles is the ability to display multiple functionalities through genetic modification so as to achieve desired therapeutic or diagnostic functions. Ferritin complexes formed from short ferritin (sFt) lacking the fifth helix can accommodate dual peptide and protein functionalities on N- and C-terminal sites in sFt monomers. The resulting double-chambered Nano Cage (DCNC) offers the potential of dual activities; these activities are augmented by the avidity of the ligands, which do not impede each other's function. Here we demonstrated proof-of-concept of DCNCs, loading the tumor-targeting proapoptotic peptide CGKRK(KLAKLAK)(2) onto the N-terminal chamber and green fluorescent protein (GFP) onto the C-terminal chamber. The resulting KLAK-sFt-GFP DCNCs were internalized into the human breast adenocarcinoma cell line MDA-MB-231 and induced apoptosis. These findings suggest that DCNCs containing various combinations of peptides and proteins could be applied as therapeutics in different diseases.