Managed floods are increasingly being promoted as a means to enhance ecological values; however, evidence for their effectiveness is often either lacking or unclear. We experimentally flooded a billabong by pumping water from an adjacent creek with the aim to promote native wetland flora and reduce the prevalence of terrestrial exotic plant species. We monitored water levels and surveyed the vegetation of three billabongs, including the one which we flooded, before and after the managed flood. Due to wet conditions, all billabongs flooded to some extent, so we assessed vegetation changes against a gradient of flooding duration (which was extended in the target billabong). The change in cover of amphibious vegetation was more positive, and the change in cover of exotics was more negative, with increasing flooding duration, with these effects amplified in the deliberately flooded billabong. Our study provides evidence for the use of managed floods to maintain and promote native wetland vegetation.