Novel classes of jellyfish-shaped amphiphilic dendrimers composed of 7 hydrophilic poly(ethylene glycol) (PEG) arms and 14 hydrophobic polyester dendrons with beta-cyclodextrin (beta CD) as the core molecule were synthesized by a facile method. Seven PEG chains were first conjugated to the C-6 positions of native beta CD. Subsequently, dendritic polyester architectures were constructed from the remaining 14 secondary hydroxyl groups at C-2 and C-3 positions of the beta CD moiety, resulting in jellyfish-shaped amphiphilic dendrimers of different generations (7PEG-beta CD-Gx) with well-defined molecular structures. The amphiphilic dendrimers self-assembled into different morphologies dependent upon the hydrophilic fraction of the dendrimers, and very surprisingly, the fourth-generation dendrimers consisting of only several percent of PEG could form aggregates with extremely narrow size distributions.