The livelihoods of millions of rice farmers in Vietnam’s Mekong Delta have become increasingly vulnerable due to reduced rainfall and the resulting water stress. In this context, promoting water-saving practices, such as alternate wetting and drying technology, is vital to sustain rice production and enhance people’s resilience to climatic changes in the Delta. Since this technology is not widely applied in the region, this study hypothesized that a precise water measurement using the Internet of Things technology could facilitate the uptake of the alternate wetting and drying rice cultivation practice. The study applied a rigorous research design to assess the differential benefits of applying the technology with sensors. Participating farmers were divided into three treatment groups that produced rice using either the continuously flooded irrigation technique, manual alternate wetting and drying tubes, or tubes with sensors. The on-farm trials’ results showed that the precise water level measurements with the sensors allowed the farmers to maximize the benefits from alternate wetting and drying irrigation. The experimental results indicated an additional 13-20% of water savings over manual alternate wetting and drying. The technology also reduced irrigation energy costs by 25% and moderately enhanced rice yields by 2-11%. This pilot was the first to demonstrate in a large-scale open-field trial that it is feasible and beneficial for smallholder farmers to apply cutting-edge Internet of Things technology to increase water use efficiency in their rice farms. The technology adoption would significantly contribute to sustaining the agriculture-based livelihoods of people in the Delta.