IL‐27 has been shown to exhibit both pro‐ and anti‐inflammatory properties; it favors mouse naïve CD4⁺T‐cell differentiation into Th1 cells to the detriment of Th17 and Th2 skewing and regulates IL‐10 and IL‐17 production by human CD4⁺ T cells. Moreover, IL‐27 promotes proliferation and cytotoxic functions of mouse CD8⁺ T lymphocytes, but no data are available on human CD8⁺ T cells. We investigated the impact of IL‐27 on human CD8⁺T cells. In contrast to mouse T cells, the IL‐27 receptor (IL‐27R), composed of T cell cytokine receptor (TCCR) and gp130, was detected on a greater percentage of human CD8⁺ than CD4⁺ T cells and these proportions increased upon polyclonal activation. IL‐27 induced rapid STAT1 and STAT3 signaling, enhanced STAT1 protein levels, and induced SOCS1 and SOCS3 expression in a STAT1‐dependent manner by human CD8⁺ T cells. Addition of IL‐27 to α‐CD3‐activated naïve CD8⁺ T cells significantly increased T‐box transcription factor expression levels, cell proliferation, and IFN‐γ and granzyme B production leading to increased CD8⁺ T‐cell‐mediated cytotoxicity. These results demonstrate that IL‐27, a rapidly produced cytokine by activated APC, has a profound impact on human naïve CD8⁺T cells, driving them to become highly efficient Tc1 cells.