Performing offline sample preparation steps to determine bioactive compounds from natural products takes a long time to obtain results, is laborious, and more error-prone than performing the extraction, purification, and analysis processes on-line. Thus, this work aimed to extract anthocyanins from dried and defatted açaí pulp using a green technology based on the coupling of pressurized liquid extraction (PLE) with in-line purification through solid-phase extraction (SPE) and on-line analysis by high-performance liquid chromatography (HPLC). For that, lab-scale equipment assembled at BIOTAR/FEA/UNICAMP was employed. Critical parameters that affect the extraction efficiency and purification were investigated and optimized by response surface methodology (RSM). PLE was performed with acidified water at different pH (2.0, 4.5, and 7.0) and temperature (40, 80, and 120 °C) at 15 MPa, 2 mL/min, and solvent-to-feed mass ratio equal to 40. SPE was carried out in a packed column with the adsorbent PoraPak™ Rxn. Different ethanol concentrations (50, 75, and 100%) and temperatures (30, 40, and 50 °C) were applied for the anthocyanins elution at 2mL/min. The optimal conditions determined by the RSM were: 71 °C and pH equal to 2 for PLE; and 30 °C and 50% ethanol for SPE. In addition, the optimal conditions were validated (91% close to the predicted value.), confirming the methodology efficiency to obtain anthocyanins. Beyond, PLE was compared to conventional extraction methods, presenting the highest anthocyanins yield (3.01 mg/g), and PLE+SPE produced an extract 5-fold more concentrated than PLE alone. Furthermore, PLE and SPE coupled to on-line HPLC showed to be feasible to extract, purify, and analyze natural products simultaneously. Therefore, the newly developed method can prepare samples and perform on-line HPLC of different anthocyanin classes from different raw materials.