Polarization-sensitive optical techniques offer a powerful, label-free window into the micro- and nano-scale architecture of biological tissues, probing key parameters such as scatterer size, shape and refractive index, as well as bulk birefringence and optical activity. However, in highly scattering media this contrast is often degraded by multiple-scattering-induced depolarization and limited penetration depth. Tissue optical clearing (TOC) techniques address these limitations by matching refractive indices within heterogeneous tissue, reducing dehydration-induced refractive-index gradients. These enhancements translate into deeper penetration, higher spatial resolution and contrast for a host of complementary imaging modalities while also providing a means to monitor the clearing process itself. Here, we review the intersection of polarization-sensitive optical methods and TOC. We summarize the principal physicochemical mechanisms underpinning TOC, and survey both ex vivo and in vivo biocompatible optical clearing agents (OCAs) and delivery approaches. We then discuss how polarization metrics can sensitively track microstructural changes during optical clearing, opening new paths for optimizing OCA formulations and for quantitative, high-resolution studies of tissue morphology and pathology in biomedical research and diagnostic applications.