BACKGROUND The flowers and peels of cactus Opuntia ficus‐indica (OFI) are by‐products generally discarded. Their beneficial properties have been linked to the chemical composition without taking into account its transformations during digestion. This study evaluated and compared the phenolic composition, antioxidant and antiacetylcholinesterase activities of OFI peel and flower teas before and after in vitro gastrointestinal digestion. RESULTS Results showed that OFI peel tea was a source of natural phenolic compounds and carotenoids, while OFI flower tea was a source of flavonoids. Both OFI peel and flower teas exhibited high antioxidant activities (AAs) measured by several tests [1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH•), reducing power (RP), hydrogen peroxide scavenging activity (HPSA)]. Flower teas presented a higher antiacetylcholinesterase inhibition percentage than peel teas. Significant decreases of acetylcholinesterase and AAs were obtained under in vitro gastrointestinal digestion. Fourteen phenolic compounds typical of phenolic acids and flavonoids were identified in both teas. These compounds seemed to be more affected by pancreatic than by the gastric conditions. CONCLUSION OFI peel tea has been found as a source of natural phenolic compounds and carotenoids, while OFI dry flower tea as a source of flavonoids. The OFI flower tea phytochemicals were more stable than peel tea during the digestive process. These findings suggest that peels and flowers of OFI should be considered as sources of healthy ingredients. © 2022 Society of Chemical Industry.