| Name | Other Name | Family | Nativ Name | ISO6391 Code | ISO6392T Code | ISO6392B Code | ISO6393 Code | Notes |
|---|---|---|---|---|---|---|---|---|
| Kuanyama | Kwanyama | Niger–Congo | Kuanyama | kj | kua | kua | kua | |
| Kazakh | Turkic | қазақ тілі | kk | kaz | kaz | kaz | ||
| Kalaallisut | Greenlandic | Eskimo–Aleut | kalaallisut; kalaallit oqaasii | kl | kal | kal | kal | |
| Central Khmer | Austroasiatic | ខ្មែរ; ខេមរភាសា; ភាសាខ្មែរ | km | khm | khm | khm | also known as Khmer or Cambodian | |
| Kannada | Dravidian | ಕನ್ನಡ | kn | kan | kan | kan | ||
| Korean | Koreanic | 한국어 | ko | kor | kor | kor | ||
| Kanuri | Nilo-Saharan | Kanuri | kr | kau | kau | kau + 3 | macrolanguage | |
| Kashmiri | Indo-European | कश्मीरी; كشميري | ks | kas | kas | kas | ||
| Kurdish | Indo-European | Kurdî; كوردی | ku | kur | kur | kur + 3 | macrolanguage | |
| Komi | Uralic | коми кыв | kv | kom | kom | kom + 2 | macrolanguage |