Most of the self-assembly studies have hitherto explored the aqueous media as fluid phase for self-assembly of amphiphilic biomacromolecules, wherein architectural modification of biomolecules is generally a prerequisite for self-assembly of modified biomolecules. We demonstrate for the first time that ionic liquids can act as nonaqueous designer solvents to self-assemble amphiphilic biomacromolecules without requiring their prior modification. To this end, we show that enzyme (phytase) molecules self-assembled in the presence of an appropriate ionic liquid, resulting in the formation of enzyme capsules. Phytase capsules synthesized using this approach were further used as templating nanoreactors for the synthesis of enzyme-containing hollow silica nanocontainers. In situ immobilized phytase enzyme in the silica nanocontainers, when subjected to enzyme-reusability application, establishes them as excellent reusable biocatalysts.