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Hafnia‐based ferroelectric tunnel junctions (FTJs) hold great promise for nonvolatile memory and emerging data storage applications. In this article, a large tunnel electroresistance effect with ultrathin Hf_0.5Zr_0.5O₂ (HZO) barrier based FTJs is reported. Robust ferroelectricity is achieved with ≈1 nm films by stabilizing the rhombohedral polar phase of HZO (R‐HZO) through a large compressive strain, induced by growing the film epitaxially on a SrTiO₃ (001) substrate. The OFF/ON ratio of the junction resistance at zero bias is about 135 with ≈1 nm thick barrier, which increases to ≈10⁵ with increasing the barrier thickness to ≈2.5 nm. The resistance‐area product (RA) of tunnel junctions is reduced by nearly three orders of magnitude by using an ≈1 nm R‐HZO barrier as compared with typically reported RA values for doped‐HfO₂ barrier based FTJs, which significantly improves signal‐to‐noise ratio during the …