Consumers are increasingly concerned about cosmetic ingredients’ origin, looking more than ever to sustainable and greener formulations. The Natural Park of Montesinho, located in Portugal, is characterized by an enormous fauna and flora diversity. Among them, beeswax and strawberry trees (Arbutus unedo) have attracted the cosmetic researchers’ interest due to their bioactive compounds’ richness, particularly fatty acids and phenolic compounds. The main goal of this study was to develop an innovative cosmetic product with antioxidant properties composed by both matrices. Briefly, samples were obtained in the Natural Park of Montesinho in October 2022. Beeswax was analysed for lipid profile and contaminants, while extracts were obtained from fruits by ultrasound-assisted extraction (UAE) using water as a solvent. The effect of extraction time (15–90 min) was studied on the total phenolic content (TPC), in vitro antioxidant/antiradical activity, and reactive oxygen species (ROS) scavenging capacity. The beeswax lipid profile presented a high incidence of palmitic, oleic, and linoleic acids. The extract obtained at 60 min presented the highest TPC (30.27 mg GAE/g dw) and antioxidant/antiradical activities (ABTS = 30.36 mg AAE/g dw; DPPH = 43.83 mg TE/g dw; FRAP = 415.61 µmol FSE/g dw). An IC₅₀ of 19.78 µg/mL was achieved for the hypochlorous acid, while for superoxide radical and peroxyl radical the IC₅₀ were, respectively, 90.51 µg/mL and 0.19 µmol TE/mg dw. The phytochemical profile revealed a high content of gallic acid, and catechin and its derivatives. The hydrophilic cream developed revealed ideal technological parameters, particularly its stability.