Receptor-mediated endocytosis of proteins is a fundamental process in cells, crucial for maintaining cellular homeostasis and regulating signal transduction. This process is divided in to two categories, clathrin dependent and clathrin independent, each involving intricate steps and regulatory factors. Post-translational modifications, cofactors, and signaling pathways further modulate the efficiency and specificity of endocytosis, adding complexity to its regulation. Dysregulation of receptor-mediated endocytosis is implicated in various diseases, highlighting the importance of understanding its mechanisms. Insights into these processes offer valuable perspectives on how receptors function in health and disease states, potentially revealing new therapeutic targets. Several advanced techniques like fluorescence microscopy, immunofluorescence staining, live-cell imaging, biochemical assays, electron microscopy, molecular docking, chromatin immunoprecipitation, RNA interference (RNAi), and cryo-electron microscopy are developed to study receptor activities and endocytosis dynamics. Furthermore, in this book chapter we have discussed various cutting-edge methodologies such as specific hybridization internalization probe (SHIP), PhotonSABER, confocal microscopy, bioluminescence resonance energy transfer (BRET), and fluorescence resonance energy transfer (FRET) have emerged as powerful tools in this field. These techniques facilitate detailed investigations into molecular mechanisms underlying receptor-mediated signaling pathways and their dysregulation in disease. They hold promise for advancing our understanding of disease pathology, improving diagnostic capabilities, and identifying novel therapeutic targets aimed at modulating receptor-mediated endocytosis for therapeutic benefit.