Large‐pore mesoporous silica nanoparticles (MSN) were prepared and functionalized to serve as a highly robust and biocompatible delivery platform for platinum–acridine (PA) anticancer agents. The material showed a high loading capacity for the dicationic, hydrophilic hybrid agent [PtCl(en)(N‐[acridin‐9‐ylaminoethyl]‐N‐methylpropionamidine)] dinitrate salt (P1A1) and virtually complete retention of payload at neutral pH in a high‐chloride buffer. In acidic media mimicking the pH inside the cell lysosomes, rapid, burst‐like release of P1A1 from the nanoparticles is observed. Coating of the materials in phospholipid bilayers resulted in nanoparticles with greatly improved colloidal stability. The lipid and carboxylate‐modified nanoparticles containing 40 wt % drug caused S‐phase arrest and inhibited cell proliferation in pancreatic cancer cells at submicromolar concentrations similar to carrier‐free P1A1. The most striking feature of nanoparticle‐delivered P1A1 was that the payload did not escape from the acidified lysosomal vesicles into the cytoplasm, but was shuttled to the nuclear membrane and released into the nucleus.