In this work we pilot a methodology to value the annual coastal protection benefits provided by mangroves in the Philippines and identify where these natural coastal defenses deliver the greatest protection. This is the first rigorous, engineering-based, nationwide evaluation of the effectiveness of mangrove habitats as natural defenses. By comparing flood damages for scenarios with and without mangroves, the study estimates the socioeconomic benefits for protecting people and property, to inform conservation and disaster risk reduction policies. Without mangroves, flooding and damages to people, property and infrastructure in the Philippines would increase annually around 25%. These habitats reduce flooding to 613,500 people/year, 23% of whom live below the poverty line. They also avert damages to 1 billion US$/year in residential and industrial property. If mangroves were restored to their 1950 distribution, there would be additional benefits to 267,000 people annually, including 61,500 people below poverty and an additional 453 mill. US$ in avoided damages. Currently, mangroves prevent more than 1.7 billion US$ in damages for extreme events (1-in-50-year). Ultimately, rigorous economic estimates of critical ecosystem services like this will help the national government to integrate the value of mangroves to people, into their national accounting systems.