Carborane shows high levels of hydrophobicity, thermal stability, and chemical stability. The hydrophobicity of carborane has been used to form interactions with the hydrophobic core of bioactive proteins. We have designed and synthesized carborane-bearing pullulan using carborane as a hydrophobic core to prepare physically crosslinked nanogels. The resulting amphiphilic polysaccharide formed stable self-assembled nanogels through a complex network of hydrophobic interactions.