Abstract Light‐harvesting is an indispensable process in photosynthesis, and researchers have been exploring various structural scaffolds to create artificial light‐harvesting systems. Herein, a light‐harvesting system (LHS) is constructed by AuNCs. First, ionic liquid 1‐Dodecyl‐3‐methylammonium bromide (C 12 mimBr) and Ba 2+ are used to co‐assembly with 6‐aza‐2‐thiothymine (ATT) modified AuNCs to get ATT‐AuNCs/C 12 mimBr/Ba 2+ (M‐AuNCs) with network superstructures and improved emission efficiency. This makes M‐AuNCs applicable for aqueous LHS. Furthermore, the green‐emitting network serves as energy donors, and red‐emitting positive dyes (rhodamine B) act as acceptors. An efficient energy transfer process occurs between them with an energy transfer efficiency of 94.1%. Significantly, sequential energy transfer can also be realized with the further addition of deep‐red emitting dye (sulforhodamine 101). Notably, the system can only be constructed by M‐AuNCs instead of mono‐dispersed ATT‐AuNCs. Based on this, a FRET‐triggered logic gate is established, in which C 12 mimBr and Ba 2+ can be considered as energy switches to turn on/off the logic gate. Therefore, this work not only fabricates an AuNCs‐based LHS through sequential energy transfer, but also develops a FRET‐triggered logic gate, which has potential application in molecular recognition and information encryption.