With the aim of quality improvement, the effects of foliar application of phenylalanine at 5 concentrations on grape (Vitis vinifera cv. Qızıl Uzum) berry compositions were studied. The studied parameters included antioxidant activity, total phenolics, total flavonoids, total anthocyanin, catalase, phenylalanine ammonia-lyase enzyme activity, and phenolic compounds content based on HPLC analyses (myricetin, quercetin, kaempferol, syringetin, catechin, gallic acid, caffeic acid, p-coumaric acid, resveratrol). Phenylalanine at 1000 μM increased total phenols, flavonoids, anthocyanins, and PAL enzyme activity. In addition, HPLC analysis revealed a significant accumulation of individual phenolic compounds by phenylalanine treatment. The highest values were recorded at 100 and 500 μM phenylalanine treatments. Real-time quantitative RT-PCR results showed that the expression of PAL and CHS genes was induced by phenylalanine. The highest PAL and CHS gene expression was observed at 500 μM and then at 1000 μM phenylalanine.