Background: Blogs are being used increasingly to disseminate nutrition information to consumers, including by registered dietitians (RDs). Guidelines in authoring blogs are important for dietetics professionals so that they effectively communicate evidence-based nutrition information in this format. Objective: The aim of this study was to obtain consensus from experts comprising RDs with active blog-writing experience on a set of guidelines for use by RDs when authoring a healthy eating or nutrition information blog. Design: A modified e-Delphi technique with a consensus-based approach was used in this study undertaken between June and October 2019. The purpose-built, pilot-tested e-Delphi survey was informed by a literature review and included statements from 3 domains comprising blog readers and communication; purpose and healthy eating messages; and structure, voice, and tone. Expert participants were identified purposively and via snowballing. In each survey round, statements that achieved 80% consensus were accepted. Participants/setting: A total of 19 experts consented to participate. Experts resided in the United States, Australia, and United Kingdom. Experts were mainly women aged between 30 and 49 years and working in private practice and/or research or teaching areas of nutrition and dietetics. Results: Across 3 domains, a total of 33 statements were accepted, comprising a final set of guidelines named the P.O.S.T (purpose, community, structure, and tone) Guidelines for Nutrition Blogs. Conclusions: Consensus from a panel of dietetics experts resulted in the P.O.S.T Guidelines for Nutrition Blogs, which can support RDs in authoring healthy eating blogs. This will ensure that evidence-based nutrition messages provided to consumers are engaging and effective.