Graphdiyne (GDY) is regarded as an exceptional candidate to meet the growing demand in many fields due to its rich chemical bonds, highly π‐conjugated structure, uniformly distributed pores, large surface area, and high inhomogeneity of charge distribution. The extensive research efforts bring about a rapid expansion of GDY with a variety of functionalities, which significantly enhance performance including photocatalysis, energy, biomedicine, etc. In this review, the synthetic strategies (in situ and ex situ approaches) that are designed to rationally functionalize GDY, including optimizing their nanostructures by surface/interface engineering with dopants or functional groups (heteroatoms/small molecules/macromolecules), and building up hierarchical GDY‐based heterostructures are highlighted. Theoretical calculations on the structural evolution and electronic characteristics after the functionalization of GDY are briefly discussed. With elaborate functionalization and rational structure engineering, functional GDY applied in a variety of emerging applications (e.g., hydrogen evolution reaction, CO2 reduction reaction, nitrogen reduction reaction, energy storage and conversion, nanophotonics, sensors, biomedical applications, etc.) are comprehensively discussed. Finally, challenges and prospects concerning the future development of GDY‐based nanoarchitectures are also presented. To exploit full potential and push the limits of graphdiyne (GDY), numerous functional GDY‐based nanoarchitectures are rationally designed with remarkably improved performances from both theoretical and experimental investigations. It is anticipated that this timely review can pave the way to new designs of functional GDY‐based nanoplatforms for next‐generation nanodevices.