T‐cell receptors (TCRs) can be genetically modified to improve gene‐engineered T‐cell responses, a strategy considered critical for the success of clinical TCR gene therapy to treat cancers. TCR:ζ, which is a heterodimer of TCRα and β chains each coupled to complete human CD3ζ, overcomes issues of mis‐pairing with endogenous TCR chains, shows high surface expression and mediates antigen‐specific T‐cell functions in vitro. In the current study, we further characterized TCR:ζ in gene‐engineered T cells and assessed whether this receptor is able to interact with surface molecules and drive correct synapse formation in Jurkat T cells. The results showed that TCR:ζ mediates the formation of synaptic areas with antigen‐positive target cells, interacts closely with CD8α and MHC class I (MHCI), and co‐localizes with CD28, CD45 and lipid rafts, similar to WT TCR. TCR:ζ did not closely associate with endogenous CD3ε, despite its co‐presence in immune synapses, and TCR:ζ showed enhanced synaptic accumulation in T cells negative for surface‐expressed TCR molecules. Notably, synaptic TCR:ζ demonstrated lowered densities when compared with TCR in dual TCR T cells, a phenomenon that was related to both extracellular and intracellular CD3ζ domains present in the TCR:ζ molecule and responsible for enlarged synapse areas.