Copper-nickel bimetallic nanoparticles (Cu-Ni BNPs) were fabricated using an eco-friendly green method of synthesis. An extract of synthesized Gazania rigens was used for the synthesis of BNPs followed by characterization employing different techniques including UV/Vis spectrophotometer, FTIR, XRD, and SEM. Spectrophotometric studies (UV-Vis and FTIR) confirmed the formation of bimetallic nanoparticles. The SEM studies indicated that the particle size ranged from 50 to 100 nm. Analysis of the BNPs by the XRD technique confirmed the presence of both Cu and Ni crystal structure. The synthesized nanoparticles were then tested for their catalytic potential for photoreduction of methylene blue dye in an aqueous medium and DPPH radical scavenging in a methanol medium. The BNPs were found to be efficient in the reduction of methylene blue dye as well as the scavenging of DPPH free radicals such that the MB dye was completely degraded in just 17 min at the maximum absorption of 660 nm. Therefore, it is concluded that Cu-Ni BNPs can be successfully synthesized using Gazania rigens extract with suitable size and potent catalytic and radical scavenging activities.