Green tea catechins have received significant attention due to their potent antioxidant activity as well as diverse biological properties. Stabilizing and protecting catechins from degradation is very important but challenging. In this work, a nanosized edible gamma-cyclodextrin-based metal-organic framework (CD-MOF) was designed and fabricated by a facile vapor diffusion route and applied for the encapsulation of a model green tea catechin, (-)-epigallocatechin gallate (EGCG) for the first time. Downsizing CD-MOF to the nanoscale is a suitable method to tackle down new applications. Significantly, the antioxidant activity results show that the CD-MOF-EGCG can remarkably enhance the antioxidant activity in alkaline solutions, as compared to that of free EGCG. Furthermore, the prepared CD-MOF-EGCG showed strong cancer cell growth inhibitory effects on C6 cells as confirmed by the cell viability assay. This work demonstrates that such safe and nontoxic nanoscale CD-MOF-based porous materials hold great promise for applications in the field of stabilization of catechins for biomedical applications.