An investigation was carried out to extract polyphenols from mango and kinnow mandarin peels for the development of functional fruit bars and their storage stability. Solvent ethanol at 50%, 80% and 100% concentration was employed for polyphenols extraction from mango and kinnow peels through ultrasound assisted extraction technique. Higher polyphenols were extracted from mango peels with comparatively more antioxidant activity than kinnow peels. Fruit bars fortified with different levels of mango and kinnow peel polyphenolic extracts subjected to ambient and refrigerated storage conditions revealed a gradual decline in total polyphenols, antioxidant activity and sensory attributes score during storage period. Microbiological parameters though increased during storage but remained well within the permissible limits. Ambient temperature storage fruit bars were discarded after three months whereas at refrigeration temperature conditions remained sensory acceptable for five months. Overall, 2% mango peel extract fortified fruit bars scored highest by the sensory panelists while 3% kinnow peel extract fortified fruit bars scored lowest. It was concluded that mango and kinnow peel extract could be utilized as ingredient for the preparation of functionl foods.