Insulating titanium dioxide finds numerous technological applications where dislocations can have profound implications for its performances. Herein, by combining advanced electron microscopy with first-principles calculations, we provide a direct atomic-resolution imaging of the core structure of a dislocation in TiO₂, and predict that individual impurity-free dislocation shows electric conductivity in otherwise insulating TiO₂. Electronic structure calculations reveals that there appears a confinement of spin-polarized conducting states within the dislocation core in a spatially connected fashion, acting as conducting pathways. Finding the local property shift at the dislocation core opens an additional avenue for manipulating dislocations as well as advances our understanding on functionalities of TiO₂.