OMB may refer to:

• East Ambae language (ISO 639-3 code: omb), an Oceanic language spoken on Ambae, Vanuatu
• Office of Management and Budget, the largest office within the Executive Office of the President of the United States
• Olympiade Mathématique Belge, a mathematical competition for students in grades 7 to 12
• OMB, a graphic design studio founded by Oscar Mariné
• Ontario Municipal Board, an independent administrative board in the province of Ontario, Canada
• Optical Media Board, a national agency under the Office of the President of the Philippines
• Oregon Marching Band, the marching band of the University of Oregon
• Oregon Medical Board, state agency responsible for establishing the rules and regulations for medicine