The present study focused on the exotic plant species Justicia californica, which is a native species of California. Phytochemicalanalysis was performed, which showed the presence of alkaloids, aminoacids, carbohydrates, glycosides, phlobatannins, and tannins in the root extract of J.californica, whereas amino acids, carbohydrates, and tannins were present in leaf and stems extract. In roots, 9.46%, and in leaf and stem, 13.35% flavonoids were found. Phenolics were found to be key phytochemicals, playing a role in antioxidant activity, which are about 8% in the sample of roots and 11.4% in the extract of leaf and stems. The DPPH assay, reducing power, and antibacterial assay was also tested, which showed the scavenging and antibacterial activity of J. californica. Thus, the preliminary study of Justicia species concluded that it can be used for medicinal purposes.