Src homology 2 (SH2) domain‐containing protein tyrosine phosphatase‐1 (SHP‐1) is a critical inhibitory regulator in T cell‐receptor (TCR) signaling. However, the exact molecular mechanism underlying this is poorly defined, largely because the physiological substrates for SHP‐1 in T cells remain elusive. In this study, we showed that adaptor protein 3BP2 serves as a binding protein and a physiological substrate of SHP‐1. 3BP2 is phosphorylated on tyrosyl residue 448 in response to TCR activation, and the phosphorylation is required for T cell signalling, as indicated by transcriptional activation of nuclear factor activated in T cells (NFAT). Concurrently, phosphorylation of Tyr566 at the C‐terminus of SHP‐1 causes specific recruitment of 3BP2 to the phosphatase through the SH2 domain of the adaptor protein. This leads to efficient dephosphorylation of 3BP2 and thereby termination of T cell signaling. The study thus defines a novel function of the C‐terminal segment of SHP‐1 and reveals a new mechanism by which T cell signaling is regulated.