Ferroelectricity in CMOS-compatible hafnia (HfO₂) is crucial for the fabrication of high-integration nonvolatile memory devices. However, the capture of ferroelectricity in HfO₂ requires the stabilization of thermodynamically metastable orthorhombic or rhombohedral phases, which entails the introduction of defects (e.g., dopants and vacancies) and pays the price of crystal imperfections, causing unpleasant wake-up and fatigue effects. Here, we report a theoretical strategy on the realization of robust ferroelectricity in HfO₂-based ferroelectrics by designing a series of epitaxial (HfO₂)₁/(CeO₂)₁ superlattices. The designed ferroelectric superlattices are defects free, and most importantly, on the base of the thermodynamically stable monoclinic phase of HfO₂. Consequently, this allows the creation of superior ferroelectric properties with an electric polarization >25  μC/cm₂ and an ultralow polarization-switching energy barrier at ∼2.5  meV/atom. Our work may open an avenue toward the fabrication of high-performance HfO₂-based ferroelectric devices.