Novel cationic poly(ester amide) dendrimers have been synthesized by copper(I) azide–alkyne cycloaddition (CuAAC) of a tripropargylamine core and azide-terminated dendrons, in turn prepared by iterative amide coupling of the new monomer 2,2′-bis(glycyloxymethyl)propionic acid (bis-GMPA). The alternation of ester and amide groups provided a dendritic scaffold that was totally biocompatible and degradable in aqueous media at physiological and acidic pH. The tripodal dendrimers naturally formed rounded aggregates with a drug that exhibited low water solubility, camptothecin, thus improving its cell viability and anti-Hepatitis C virus (anti-HCV) activity. The presence of numerous peripheral cationic groups enabled these dendrimers to form dendriplexes with both pDNA and siRNA and they showed effective in vitro siRNA transfection in tumoral and non-tumoral cell lines.