The search for new control methods over light-matter interactions is one of the engines that advances fundamental physics and applied science alike. A specific class of light-matter interaction interfaces are setups coupling photons of distinct frequencies via matter. Such devices, nontrivial in design, could be endowed with multifunctional tasking. Here we envisage for the first time an optomechanical system that bridges optical and robust, high-frequency X-ray photons, which are otherwise notoriously difficult to control. The X-ray-optical system comprises of an optomechanical cavity and a movable microlever interacting with an optical laser and with X-rays via resonant nuclear scattering. We show that optomechanically induced transparency of a broad range of photons (10 eV-100 keV) is achievable in this setup, allowing to tune nuclear X-ray absorption spectra via optomechanical control. This paves ways for metrology applications, e.g., the detection of the 229Thorium clock transition, and an unprecedentedly precise control of X-rays using optical photons.