In this study, the controlled synthesis of highly stable Ag₅₆ clusters was achieved using 4-vinylbenzoic acid (p-VBA) and tert-butyl mercaptan as ligands by accurately tuning reaction parameters such as temperature and solvent. Additionally, intermediates Ag₂₀, Ag₃₁, Ag₃₂, along with the dimers of Ag₃₁/Ag₃₂, Ag₃₀-bpbenz (bpbenz: 1,4-di(4-pyridyl)benzene), and Ag₃₁-bpe (bpe: 1,2-bis(4-pyridyl)) were successfully captured. This series of nanoclusters exhibited a distinctive fluorescence aggregation-induced redshift phenomenon owing to the π–π interactions of the ligand. Additionally, the Ag₅₆ nanocluster serves as a near-infrared fluorescence sensor for Br⁻ and I⁻, with detection limits as low as 85 and 105 nM, respectively. This study offers new insights and methodologies for the synthesis of metal clusters and their applications in ion sensing.