BSO may refer to:

• Bilateral salpingo-oophorectomy, the surgical removal of both ovaries and both fallopian tubes
• Barents Sea Opening, an gateway to the Arctic Ocean
• British School of Osteopathy, the United Kingdom's oldest osteopathic institution
• Bismuth silicon oxide, a chemical compound that has bismuth, silicon, and oxygen
• Buthionine sulfoximine, a chemical substance inhibiting glutathione synthesis
• Brain storm optimization algorithm
• British Society of Otology, UK professional body
• , Classifying space for orthogonal group
• , Classifying space for infinite orthogonal group

• Baltimore Symphony Orchestra, Maryland, United States
• Beijing Symphony Orchestra, Beijing, China
• Berliner Sinfonie Orchester, Berlin, Germany
• Bloomington Symphony Orchestra (Minnesota), United States
• Bilkent Symphony Orchestra, Ankara, Turkey
• Birmingham Symphony Orchestra, England
• Boston Symphony Orchestra, Massachusetts, United States
• The Brian Setzer Orchestra, a United States band of the late 1990s swing revival
• British Symphony Orchestra, the name of a number of symphonic ensembles since c1905
• Bournemouth Symphony Orchestra, Poole, Dorset, England

• Basco Airport, Batanes, Philippines
• Basildon railway station, station code

• BSO, a European information technology company founded by Eckart Wintzen, now a part of Atos
• Baloch Students Organization, Balochistan, Pakistan
• Bank of Syria and Overseas, Syria
• Basque Statistics Office
• Bicycle shaped object, a cheaply produced, poor quality bicycle sold in mainstream stores
• Basilian Salvatorian Order, a Catholic monastic community in Lebanon
• Black September Organization, a Palestinian militant group
• Brake Standard Open, a designation of British railway carriage
• Broward County Sheriff's Office, Florida, USA
• Österreichische Bundes-Sportorganisation, the Austrian Federal Sports Organization
• Buso language, the language spoken by a tribe in western Chad, by ISO 639 designation