The Lemnaceae or duckweed family comprises 37 species of smallest and simplest flowering plants. Duckweeds have a fast growth rate, can survive under a wide range of temperature and pH conditions and are easy to maintain and harvest which makes them an excellent candidate for bioremediation of wastewaters. The main objective of the present review is to extend an appreciation for the potential of living and non-living biomass of duckweed in remediating waters contaminated with heavy metals. Along with showing the detailed mechanism of phytoremediation by duckweed, the paper also discusses the enhancement of duckweed phytoremediation by the integration of transgenic technology. Furthermore, the paper explores other applications of duckweed specifically as fuel, animal feed, in human nutrition, in medicine and as a life support system. Apart from this, various disposal mechanisms for harvested duckweed have been analysed. Current understanding of removal efficiencies of several contaminants by employing duckweed is limited mainly to laboratory experiments. More concentrated and persistent efforts to develop efficient approaches for the genetic transformation of duckweeds can expand the development and utilization of duckweeds.