Proposed global definitions of whole grain as an ingredient and whole grain food are presented by the authors on behalf of the Whole Grain Initiative. Whole grains are an important pillar of healthy and sustainable diets. Internationally accepted credible definitions of whole grains as food ingredients and whole-grain foods are necessary to ensure that all global stakeholders have shared standards, and that consumers find them clear, credible, and useful. Based on widely accepted, existing definitions and new developments, the Definitions Working Group of the global Whole Grain Initiative, with experts from academia, government agencies and industry, developed definitions for global application. The key statements of the definition documents are as follows: “Whole grains shall consist of the intact, ground, cracked, flaked or otherwise processed kernel after the removal of inedible parts such as the hull and husk; all anatomical components, including the endosperm, germ, and bran must be present in the same relative proportions as in the intact kernel” and “A whole-grain food shall contain at least 50% whole-grain ingredients based on dry weight. Foods containing 25–50% whole-grain ingredients based on dry weight, may make a front-of-pack claim on the presence of whole grain but cannot be designated ‘whole grain’ in the product name”. The definition documents have been ratified by the leading international scientific associations in this area. We urge that these consensus Whole Grain Initiative definitions be adopted as the basis for definitions used by national regulatory authorities and for health promotion organisations worldwide to use in nutrition education and food labelling.