Using a set of scanning probe microscopy techniques, we demonstrate the reproducible tunneling electroresistance effect on nanometer-thick epitaxial BaTiO₃ single-crystalline thin films on SrRuO₃ bottom electrodes. Correlation between ferroelectric and electronic transport properties is established by direct nanoscale visualization and control of polarization and tunneling current. The obtained results show a change in resistance by about 2 orders of magnitude upon polarization reversal on a lateral scale of 20 nm at room temperature. These results are promising for employing ferroelectric tunnel junctions in nonvolatile memory and logic devices.