The butterfly pea flower plants are used as medicinal plants because they contain secondary metabolite compounds such as alkaloids, flavonoids, saponins, triterpenoids, and tannins that function as antibacterials. However, butterfly pea flower preparations in extract form have poor bioavailability. One of the efforts to overcome this problem is to formulate it into nanoherbal form. The purpose of this research is to synthesize nanoherbal of ethanol extract of telang flower and test its antibacterial activity. Synthesis of nanoherbal using ionic gelation method with alginate polymer and CaCl₂ cross-linking agent. There were 3 variations of alginate-CaCl₂ composition, namely (10:1); (5:1); and (2.5:1). The synthesis results in the form of purple nanoherbal colloids with optimal variation in the ratio (10:1). Nanoherbal was characterized using PSA, FTIR, and SEM. PSA test results in the form of particle size of the optimal variation of 220.4 nm as much as 100%, polydispersity index of 0.2550, and zeta potential of -22.5 mV. In the FTIR test results, the optimal variation there are groups O-H, C-H, COO^- (asymmetric), COO^- (symmetric), and C-O at wavenumbers 3415, 2931, 1620, 1411, and 1057 cm^-1. SEM test of the optimal nanoherbal resulted in a non-spherical surface morphology. Antibacterial testing of nanoherbals used the disc diffusion method and showed that nanoherbals can inhibit the growth of E. coli bacteria with a IZD value of 22.35 mm. and S. aureus bacteria with a IZD value of 12.26 mm.