Controlled synthesis of porous metal oxides with desired morphology has been motivating scientists to explore and develop new preparation methodologies. Among them, thermal decomposition of metal–organic frameworks (MOFs) has been employed for the fabrication of several metal oxides. In this work, this strategy is employed to prepare mesoporous and tetragonal zirconia (t-ZrO₂) from a metal–organic framework (UiO-66), acting as both a morphological template and a zirconium source. This process avoids the use and removal of an extra template as well as the addition of stabilizers for t-ZrO₂. After thermal decomposition at 500 °C, t-ZrO₂ inherited an octahedral morphology from the pristine precursor and possessed small nanoparticles with an average size of 3.1 nm. The derived t-ZrO₂ had a large surface area of 174 m² g⁻¹ and a pore diameter of 5–8 nm. The formation mechanism of t-ZrO₂ was also discussed. This simple and potentially universal strategy can be used to fabricate porous metal oxides with desired shape for many applications.