An aqueous extract of the shade-dried parts of Asparagus aethiopicus L. and Asparagus densiflorus (Kunth) Jessop was used to synthesize copper (CuO) nanoparticles (Cu NPs). UV-visible spectroscopy was performed to assess the formation of Cu NPs. Maximum absorbance was obtained between 310–360 nm, confirming the formation of Cu NPs. CuO NPs were effective against Pseudomonas aeruginosa (ATCC 27853), a gram-negative human pathogenic bacterium. The bacterial growth curve showed that the NPs inhibited bacterial growth. This study was conducted using different parts of the plant, such as the roots, shoots, fruits, and seeds of A. aethiopicus and the roots and shoots of A. densiflorus. The fruit and seeds of A. aethiopicus showed better results than the roots and shoots. Therefore, employing green synthetic processes inhibits the release of harmful by-products. Compared to traditional techniques of NP synthesis, the transition to the extracellular production of CuO NPs utilizing dried biomass appears to be economical and environmentally beneficial.