Olive oil production generates large quantities of by-products, which are considered waste and pose a major threat to the environment due to their complex composition and proven toxicity. Olive pomace, one of the main by-products of olive oil production, is a significant source of natural antioxidants, the most important of which are tyrosol, hydroxytyrosol and oleuropein. Due to its numerous beneficial effects on health, the main objective of this study was developing an environmentally friendly process of production of the olive pomace dry extract rich in hydroxytyrosol, tyrosol and oleuropein using a combination of ultrasonic extraction and cyclodextrin encapsulation. Functional characterization of the extracts obtained was necessary to determine their further application potential. In the first phase of the research, the methods of classical extraction, innovative ultrasonic extraction and ultrasonic extraction combined with cyclodextrin encapsulation were optimized. In the second part of the research, the applicability of the freeze-drying process and the influence of cyclodextrins on the technological and chemical properties of the dry extracts were studied. In the last phase of the research, the functional characterization of olive pomace dry extracts in advanced biological and food model systems was performed and the bioavailability of the main active polyphenolic components was determined. Optimized classical extraction yielded extracts with oleuropein as the most abundant phenolic compound (115.14 ± 0.19 mg/kg fresh olive pomace). By applying optimal ultrasonic extraction conditions in combination with cyclodextrin encapsulation, even higher yields of oleuropein (1744 mg/kg olive pomace), tyrosol (1117 mg/kg olive pomace), and hydroxytyrosol (887 mg/kg) were obtained. Encapsulation with cyclodextrin had a positive effect on the chemical composition and antioxidant activity of the extracts obtained. Among the cyclodextrins studied, the extracts encapsulated with hydroxypropyl-β-cyclodextrin and random methylated-β- cyclodextrin showed particularly good antioxidant activity and were especially effective in emulsion systems (1242 mg/g and 1422 mg/g Trolox equivalent, respectively), exhibiting significantly higher antioxidant activity than Trolox (reference antioxidant). In other models, they provided antioxidant protection comparable to commonly used synthetic antioxidants at concentrations of 2-3%. The results of the gastrointestinal model showed high bioavailability of olive pomace polyphenols, and the addition of cyclodextrins further improved the gastrointestinal stability of tyrosol.