This study reports the structures of two human γδ T cell receptor (TCR)–CD3 complexes: Vγ9Vδ2 and Vγ5Vδ1. The Vγ9Vδ2 TCR–CD3 complex is monomeric, with significant conformational flexibility in the TCR γ–δ extracellular domain and connecting peptides. A cholesterol-like molecule wedges into the transmembrane region, exerting an inhibitory role in TCR signaling. The Vγ5Vδ1 TCR–CD3 complex is dimeric, with two protomers nesting back to back through the Vγ5 domains of the TCR extracellular domains. Biochemical and biophysical assays confirm the dimeric structure, and the dimeric form is essential for T cell activation. These findings reveal the structural principles of the γδ TCR–CD3 complex, providing insights into the unique properties of γδ TCRs and facilitating immunotherapeutic interventions. The study highlights the distinct assembly mechanisms of γδ TCR–CD3 complexes, which differ from those of αβ TCR–CD3 complexes. The dimeric Vγ5Vδ1 TCR–CD3 complex is functional, while the monomeric variants are not. The structures also reveal the role of cholesterol in inhibiting TCR signaling by modulating the conformation of CD3ζ. The study provides a foundation for further investigations into the mechanisms of γδ TCR signaling and its potential applications in immunotherapy.This study reports the structures of two human γδ T cell receptor (TCR)–CD3 complexes: Vγ9Vδ2 and Vγ5Vδ1. The Vγ9Vδ2 TCR–CD3 complex is monomeric, with significant conformational flexibility in the TCR γ–δ extracellular domain and connecting peptides. A cholesterol-like molecule wedges into the transmembrane region, exerting an inhibitory role in TCR signaling. The Vγ5Vδ1 TCR–CD3 complex is dimeric, with two protomers nesting back to back through the Vγ5 domains of the TCR extracellular domains. Biochemical and biophysical assays confirm the dimeric structure, and the dimeric form is essential for T cell activation. These findings reveal the structural principles of the γδ TCR–CD3 complex, providing insights into the unique properties of γδ TCRs and facilitating immunotherapeutic interventions. The study highlights the distinct assembly mechanisms of γδ TCR–CD3 complexes, which differ from those of αβ TCR–CD3 complexes. The dimeric Vγ5Vδ1 TCR–CD3 complex is functional, while the monomeric variants are not. The structures also reveal the role of cholesterol in inhibiting TCR signaling by modulating the conformation of CD3ζ. The study provides a foundation for further investigations into the mechanisms of γδ TCR signaling and its potential applications in immunotherapy.