An ECNU-20 nanosheet zeolite of around 10 nm thickness along the c axis, with a hollow sphere morphology and IWR topology, was synthesized in a germanosilicate system using a commercially available organic amine, 1,8-diazabicyclo[5.4.0]undec-7-ene, as a structure-directing agent. DFT calculations confirmed that a preferential adsorption of these amine molecules took place on the (001) surface, leading to an oriented crystal growth. Moreover, the concentration of the amine determined the aggregation style of these nanosheets.