Selenium (Se) has been identified as an essential micronutrient for humans and animals, but a large proportion of the world's population is Se deficient, including those reliant on rice as their staple food. Biofortification of Se in rice grains is particulartly problematic in flooded rice production systems, due to the propensity for Se added at planting to revert to less available forms under reduced soil conditions.  We investigated how several fertiliser formulations and methods of application affected Se accumulation in rice grains. We analysed Se not only in grains but also in other plant tissues (leaf, culm and roots) and Se speciation in grains, which enabled a clear understanding how each treatment affected Se accumulation. We discovered that application of selenate-enriched urea to floodwater at heading stage was by far the most effective biofortification strategy for flooded rice, much more effective than foliar fertilisation or pre-plant applications of Se (either as selenate or selenite). This simple fertiliser formulation could be easily incorporated into any fertiliser management program for lowland rice production.