Endocytosis is an essential cellular process that involves the internalization of a varietyof cargo including macronutrients and transmembrane receptors. Fast endophilin mediated endocytosis (FEME) is a clathrin independent endocytic pathway that is responsible for the uptake of numerous receptors, many of which are major drug targets, including the exclusive uptake of the β1-adrenergic receptor (β1-AR). Successful internalization of cargo via FEME requires the precise execution of numerous steps including the generation of endocytic priming patches and the local polymerization of actin, at the leading edge of the plasma membrane. However, the molecular mechanisms of these steps are poorly resolved, and the actin machinery involved in FEME has been elusive. Utilizing a combination of in-cellulo and in-vitro reconstitution systems, we identify an integral role of liquid-liquid phase separation (LLPS) in various steps of FEME facilitating precise spatiotemporal recruitment of key endocytic machinery and the regulation of actin polymerization. We demonstrate that the major FEME regulator endophilin (EDP), undergoes LLPS with key binding partners, Lamellipodin (LPD) and the 3rd intracellular vi loop (TIL) of the β1-AR, facilitating the formation of protein assemblies mimicking endocytic priming sites. This phase transition is triggered by multivalent interactions between EDP’s SH3 domain and the proline rich motifs found in its binding partners. The availability of the receptor TIL, which is a marker of receptor activation, promotes LPDEDP clustering on lipid membranes demonstrating how multivalent interactions regulate protein assembly in the initiation stages of FEME. Along with the recruitment of the priming proteins for receptor engagement, a key step in FEME is the local polymerization of actin. Here, we identify VASP, a leading edge specific actin polymerase, as a FEME protein and establish its interactions with the endocytic priming complex. We identify a novel non-canonical interaction between the SH3 domain of EDP and the EVH1 and EVH2 domains of VASP. We show that multivalent interactions between VASP and LPD promotes LLPS in solution and in a lipid environment. We demonstrate that LPD-VASP condensates act as assembly centers that localize and promote actin polymerization with EDP antagonizing actin assembly. Collectively, in this thesis, I discuss the role of LLPS in various stages of Fast Endophilin Mediated Endocytosis.