MKK is mitogen-activated protein kinase kinase, an enzyme.
MKK may also refer to:
- Malmö KK, Swedish swim team from Malmö
- Main-Kinzig-Kreis, a kreis (district) in Hesse, Germany
- MKK, the IATA Airport code for Molokai Airport on the island of Molokai, Hawaii
- Mong Kok East station, Hong Kong; MTR station code MKK
- Museum für Kunst und Kulturgeschichte in Dortmund, Germany
- The Morgan-Keenan-Kellman system, a stellar classification system also known as Yerkes spectral classification