OKB is a transliteration of the Russian initials of "опытно-конструкторское бюро".
OKB may also refer to:
- okb, the ISO 639-3 code for Okobo language
- Oceanside Municipal Airport, the FAA LID code OKB
- Ostkustbanan, a 402-kilometre (250 mi) long mainline railway in Sweden