B7 or B-7 may refer to:

• Vitamin B7, Biotin
• The B7 (protein), important in the immune system
• The Douglas Y1B-7, a bomber of the United States Army Air Corps
• HMS B7, a B-class submarine of the Royal Navy
• A dj/music producer from Toronto Canada Embryon
• IATA code for UNI Airways, Taiwan
• An international standard paper size (88×125 mm), defined in ISO 216.
• Blake's 7, a BBC science fiction television series first broadcast in 1978–1981.
• Message board shorthand for banned

B7