MSB may refer to:

• Main Support Battalion, part of the U.S. Army logistics
• Maritime Services Board, former government agency in New South Wales, Australia
• Marshall Swift-Boeckh, a cost estimation services provider and subsidiary of CoreLogic
• Le Mans Sarthe Basket a French basketball team
• The Magic School Bus, series of children's books about science
• Media Stream Broadcast, a proprietary, multicast communications protocol owned by Microsoft
• 1,4-Bis(2-methylstyryl) benzene, also known as p-Bis(o-methylstyryl) benzene and abbreviated Bis-MSB, a wavelength shifting compound used in liquid scintillators
• Microsoft Surface Book
• Bureau of Investigation and Statistics (Military Investigation and Statistics Bureau), the military intelligence agency of the Republic of China before 1946.
• Millennium Seed Bank, an international conservation project for storing plant seeds
• Molecular Systems Biology, an open-access, peer-reviewed scientific journal
• Money services business, a legal term used by financial regulators to describe businesses that transmit or convert money
• Most significant bit, the bit with the highest significance in a word
• Most significant byte, the highest byte in a multi-byte number
• Mrs. Stewart's Bluing, a brand of fabric bluing agent that whitens fabrics with a dye called Prussian blue (ferric hexacyanoferrate)
• Myanmar Standard Bible, a translation of the Bible into the Burmese language
• Myndigheten för samhällsskydd och beredskap, the Swedish Civil Contingencies Agency
• MSB, the Southern Railway station code for Chennai Beach railway station, Chennai, Tamil Nadu, India