Objective To assess and develop consensus among a European panel of public health nutrition stakeholders regarding the competencies required for effective public health nutrition practice and the level of proficiency required in different practice contexts.Design A modified Delphi study involving three rounds of questionnaires.Setting European Union.Subjects Public health nutrition workforce development stakeholders, including academics, practitioners and employers, from twenty European countries.Results A total of fifty-two expert panellists (84 % of an initial panel of sixty-two Delphi participants) completed all three rounds of the Delphi study. The panellists rated the importance of fifty-seven competency units possibly required of a public health nutritionist to effectively practice (Essential competencies). Twenty-nine of the fifty-seven competency units (51 %) met the consensus criteria (≥66·7 % agreement) at the second round of the Delphi survey, with the highest agreement for competencies clustered within the Nutrition science, Professional, Analytical and Public health services competency domains. Ratings of the level of competencies required for different levels in the workforce indicated that for a public health nutrition specialist, advanced-level competency was required across almost all the twenty-nine competencies rated as essential. There were limited differences in rating responses between academics and employer panellists throughout the Delphi study.Conclusions Competencies identified as essential can be used to review current public health nutrition practices and provide the basis for curriculum design and re-development, continuing education and workforce quality assurance systems in Europe. These are all important tools for systematic and strategic workforce development.