Ferroelectric materials exhibit a spontaneous internal electrical alignment (polarization) that can be reversed with an external electric field. Thickness‐dependent transition in titanium dioxide films: dielectric to ferroelectric phase for thin (>3 nm) systems. Cross-sectional electron microscopy image showing one-nanometer-thick titanium dioxide film grown on a silicon substrate and capped with platinum metal. Ferroelectric titanium dioxide holds enormous promise for next-generation electronics. This work shows that even a ubiquitous dielectric like titanium dioxide can reveal extraordinary properties when pushed to atomic-scale thickness.