PKB is a three-letter abbreviation that may refer to:
- Państwowy Korpus Bezpieczeństwa, a Polish underground police force during World War II
- The National Awakening Party of Indonesia, from the abbreviation for its name in Indonesian
- Base dissociation constant as pKb or pKB, a chemical compound descriptive parameter
- Protein Kinase B, otherwise known as AKT, an enzyme that plays a major role in signal transduction
- Pacamor Kubar Bearings in Troy, NY domestically manufactures miniature and instrument ball bearings for aerospace, guidance, military, medical, dental, and other high precision applications.
- Mid-Ohio Valley Regional Airport in Parkersburg, West Virginia
- Package Body, filename extension (.pkb) for PL/SQL program code modules in the Oracle Database
- Personal knowledge base, a type of electronic tool for managing an individual's knowledge
- Pot calling the kettle black, in Usenet slang