FMO may refer to:
- Fenna-Matthews-Olson complex
- Fish Marketing Organisation, a statutory body of Hong Kong
- Flavin-containing monooxygenase
- Flexible macroblock ordering
- Fragment molecular orbital
- Frontier molecular orbital theory
- Münster Osnabrück Airport in North Rhine-Westphalia, Germany
- Netherlands Development Finance Company (Dutch: Nederlandse Financierings-Maatschappij voor Ontwikkelingslanden N.V.)