Consumption of cereal foods has been related to health improvement, which is partly because of their phytochemicals. To explore the functionality and effective application of barley malt, a widely consumed nutritional food, the entire phytochemical profiles and bioactivities of three common barley malt products obtained under different roasting temperatures were analyzed. Results showed that they are abundant in phenolics including flavonoids with high antioxidative activities, as displayed by cellular antioxidant activity (CAA), oxygen radical absorbance capacity, peroxyl radical scavenging capacity, and DPPH and ABTS radical scavenging assays. Among the three barley malts, the raw barley malt bound extract and the dark barley malt free extract exhibited higher CAA values, while the raw barley malt contained a negligible amount of bound phenolics. An efficacious antiproliferation capacity of the dark barley malt free extract was detected in Caco-2 cells. Results also provide an insight into the positive attributes of thermal processing for the biofunctionality of barley malts, especially through the tuning of the accessibility and variability of beneficial phytochemicals.