Green and environmentally eco-friendly technique for synthesizing nanoparticles are being widely developed. The purpose of this study was to use three species of macroalgae, including Ulva lactuca, Ulva Flexuosa, and Padina australis, for the synthesis of silver nanoparticles, which were confirmed using UV-Visible spectrometry and Fourier transform infrared (FTIR) spectrometry. The highest absorption wavelength for Ulva lactuca and Ulva Flexuosa species was 400 nm, whereas Padina australis had the highest absorption at a wavelength of 480 nm. The FTIR spectrum showed the presence of functional groups in the reduction of silver ions. Therefore, the green synthesis of nanoparticles by macroalgae is safe, environmentally eco-friendly and a suitable alternative to chemical synthesis of silver nanoparticles.