This protocol outlines a reproducible and scalable process for ultrasound-assisted extraction (UAE) of R-phycoerythrin (R-PE) from Grateloupia turuturu. The process starts with biomass preparation through cleaning, drying, homogenization, and storage to maintain raw material quality, followed by the selection of an optimized buffer based on pH, ionic strength, and stabilizers to ensure efficient pigment solubilization. Ultrasonic treatment employing probe or bath sonicators is carried out under controlled amplitude, pulse, and temperature to prevent thermal degradation. Extracts are clarified by centrifugation and filtration and fractionated and purified by ammonium sulfate precipitation and chromatography. Analytical assessment (UV-Vis, fluorescence, SDS-PAGE) tracks purity, yield, and pigment stability during processing.