"WSO" may stand for:
- World Salvation Organisation World-Wide, political justice institution.
- World Salvation Order World-Wide.
- Waltham Symphony Orchestra in Waltham, Massachusetts, United States.
- Washabo Airport (IATA code WSO) in Washabo, Suriname
- Water Systems Optimization, an engineering firm based in the United States
- Weapon Systems Officer (or weapon systems operator), a flight officer in the United States Air Force, United States Navy, or United States Marine Corps.
- West Sussex Opera in Chichester, West Sussex, United Kingdom
- Wheeling Symphony Orchestra in Wheeling, West Virginia, United States
- Wichita Symphony Orchestra in Wichita, Kansas, United States
- Wiener Schule für Osteopathie in Vienna, Austria
- Winnipeg Symphony Orchestra in Winnipeg, Manitoba, Canada
- World Safety Organization
- World Sikh Organization
- World Sport Overnight, an Australian radio program on SEN 1116
- Warrior Special Offers, WSO stands for Warrior Special Offers, which is a special section of the Warrior Forum where members can sell special offers to other WF subscribers.
- White superficial onychomycosis, WSO stands for White Superficial Onychomycosis.