In this study, we used the Agrobacterium tumefaciens–mediated transformation approach to transfer the activity of the cyanobacterial cyanase enzyme into the micro-alga, Chlamydomonas reinhardtii. In transgenic C. reinhardtii strains, the recombinant cyanase enzyme was proven to be active. In comparison to wild-type control, transgenic type demonstrated higher rates of ammonia release, reduced loss of pigmentation, and a lower percentage of growth retardation when varied amounts of cyanide (up to 200 ppm) were applied to the growth medium. Moreover, cyanase activity increases as concentration of cyanide increase especially in case of transgenic. The maximum activity was indicated in presence of 100 mg/l cyanide it reached eight folds more than wild activity at the same cyanide concentration.  Results of this study provide an effective eco-friendly phytoremediation system for detoxification of cyanide using micro-alga compared to previously reported conventional system for removal of cyanide compounds, Also, some factors are taken in consideration like different pH, contact time and the transgenic type has been the priority for removal cyanide at wide range of pH with two folds more than wild type.