Yellow camellia, with its golden yellow flowers, is rare in the world. Most studies of yellow camellia have focused on its ornamental properties; however, there are fewer published studies on its medical values. The purpose of this study was to define the chemical constituents and the biological potential of the water extract of leaves in six species of yellow camellia. The data showed that Camellia murauchii had significantly higher total catechins and total polyphenol content than others; Camellia euphlebia had the highest total amino acids and γ-aminobutyric acid. The results indicated that Camellia tunghinensis exhibited the highest free radical scavenging capacity and showed potent anticancer activities. Camellia nitidissima had stronger inhibitory effect than other species on fatty acid synthesis. In addition to catechins, 3-p-coumaroylquinic acid, kaempferol-3-O-glucoside, and quercetin-3-O-glucoside were detected in C. tunghinensis using liquid chromatography-tandem mass spectrometry. Taken together, yellow camellias possess biological activity and are worthy of continued study.