In response to growing concerns about water pollution due to uncontrolled discharges of industrial dyes, this study focused on synthesizing iron nanoparticles through a green synthesis process using Peumus Boldus extract. The objective was to evaluate the capacity of these nanoparticles to remove crystal violet, which is known for its toxicity and degradation resistance. Green synthesis, based on using plant extracts as reducing and stabilizing agents, offers an environmentally friendly alternative to traditional methods that typically rely on energy-intensive toxic chemical agents. The synthesized nanoparticles were characterized using techniques, including UV–Vis spectroscopy to assess the formation of Fe nanoparticles and transmission electron microscopy to determine their morphology and size, among others. Regarding applicability, the Fe nanoparticles were tested for the removal of crystal violet under varying pH, nanoparticle dosage, and contact time conditions. Results showed the successful synthesis of Fe nanoparticles with Peumus boldus extract without contaminant chemicals. More than 50% of Fe nanoparticles presented an apparent size between 4 and 8 nm, and X-ray diffraction showed that the main crystalline phases corresponded to maghemite and magnetite. Moreover, crystal violet removal was most efficient at pH 10, with a dosage of 16 mg (0.8 g/L) of FeNPs and a contact time of 240 min, achieving 80%. This research highlights the potential of green synthesis as a more sustainable and less polluting technique for nanoparticle production and potential application in crystal violet removal. However, more research is needed for large-scale production.