Fortification of oatmeal cookies with ingredients that are physically more attractive and functional is an interesting breakthrough for improving oatmeal cookies to be a favourite healthy food. Green tea was considered to be a food fortification because of its phytochemical content, which is beneficial to health. This study was aimed at getting more insight into the effect of green tea powder (GTP) fortification on physical (texture and colour), chemical (moisture, fat, ash, protein, carbohydrates, crude fibre content, and calories) and hedonic characteristics of oatmeal cookies. The treatments in this study were 5 levels of GTP fortification (each repeated 4 times) i.e., 0, 2, 4, 6, and 8% into the cookie’s dough. There was a significant effect (p≤0.05) of GTP fortification on the texture, colour, ash, fat, crude fibre, and total calorie products. The 2% GTP fortification in oatmeal cookies was the most preferred by the panellists, because the higher percentages of GTP affected the more bitter taste and harder texture. Fortification of oatmeal cookies with 6% GTP produces the final product, namely green tea oatmeal cookies (GTOC), which are low in fat and carbohydrates but high in fibre and protein content. GTP fortification can improve the oatmeal cookie's functional properties