Hazelnut skin is the thin and brown outer tissue layer, completely surrounds the hazelnut kernel and is released as a food by-product during the roasting process. Beyond its diverse composition including dietary fiber, phenolic compounds, flavonoids, vitamins, and minerals, hazelnut husk demonstrates substantial antioxidant activity. The chemical composition and the nutritional value of hazelnut and hazelnut skin can vary according to hazelnut varieties and the region where they grow. In this study, the chemical profile and antioxidant activity of skins from hazelnut grown in Giresun in the Black Sea Region of Türkiye were determined and its potential for use as a functional food component was investigated. Hazelnut skin samples extracted with different solvents such as acetone/methanol and ethanol/methanol, were found to have total phenolic compounds equivalent to 437.45 GAEq (mg GA/g sample) and 307.38 GAEq (mg GA/g sample), respectively. The fat content of the hazelnut skin was found to be 35.1% by mass on the dry matter, and the ratio of dietary fiber was found to be 53.5%. In addition, the total antioxidant value was calculated in samples extracted with different solvents that was found at 3.38 ± 0.2 mmol TE/g – 2.67 ± 0.1 mmol TE/g, respectively. Functional cake enriched with hazelnut skin was made, and sensory analysis studies of this functional product were also carried out.