The leaves of Juglans regia L. (walnut tree) are a rich source of bioactive phenolic compounds, particularly flavonoids and phenolic acids, which can be used in cosmetic applications due to their antioxidant properties. Conventionally, these compounds are extracted using volatile organic solvents. This study focuses on a more sustainable approach by designing a heat-assisted extraction process using aqueous solutions of eutectic solvents (ES) composed of cosmetic-compatible ingredients aiming for direct incorporation into cream formulations. In this context, aqueous solutions of the ES betaine + urea and betaine + 1,3-propanediol (PPD) were selected, considering their potential as cosmetic ingredients. The screening process targeted the maximum extraction yield of phenolic compounds (phenolic acids and flavonoids), quantified by HPLC-DAD. The selected variables were water content (25, 50 and 75 % in weight) and the molar proportion of the ES components. For comparison purposes, pure water was used as a reference solvent.The total phenolic content ranged between 5.5 and 14.6 mg/g of dry plant. Betaine:urea (2:1), betaine:PPD (1:2), betaine, and PPD, all with 50 % water mass percentage, were among those resulting in higher extraction yields and were further selected for bioactivity analysis. The system containing betaine presented the best antioxidant capacity, analysed through ferric reducing power, DPPH radical scavenging, and TBARS assays. The extracts obtained with PPD presented the highest antimicrobial activity against gram-positive and gram-negative bacteria, and yeast. The results show the potential of using binary aqueous mixtures of betaine, or 1,3-propanediol, which are simple ingredients in cosmetics formulations, to efficiently extract phenolic compounds from a natural matrix. Moreover, the bioactivity results, particularly in the antioxidant dimension, support using J. regia leaves as a source of natural antioxidants.