Optical metasurfaces (OMSs), planar arrays of meticulously designed meta-atoms, are renowned for remarkable capabilities in manipulating the polarization state of light at subwavelength scales. Nevertheless, most OMS-empowered polarization optics remain static, featuring well-defined optical responses determined by their configurations set during fabrication. Here, we demonstrate a MEMS-OMS-based dynamic linear polarizer (DLP) with an electrically controlled extinction ratio, which is tunable in a fast and reversible fashion, by combining an anisotropic plasmonic OMS with a thin-film piezoelectric MEMS mirror. Capitalizing on the MEMS-OMS DLP, we further implement voltage-controlled grayscale imaging and vector vortex beam generation under linearly and circularly polarized excitations, respectively. Our MEMS-OMS DLP design could enable adaptive photonic systems for advanced applications in optical image encryption, displays, and beyond.