| Airline Name | ICAO | IATA | Callsign | Country |
| K2000 Airlines | Australia | |||
| Kabo Air | QNK | Nigeria | ||
| Kahama Mining Corporation | Tanzania, United Republic Of | |||
| Kalair | United States | |||
| Kalitta Air | CKS | K4 | CONNIE | United States |
| Kallat El-Saker Air Company | KES | KALLAT EL SKER | Libyan Arab Jamahiriya | |
| Kam Air | KMR | RQ | KAMGAR | Afghanistan |
| Kampuchea Airlines | KMP | KT | Cambodia | |
| Kar-Air | KAR | KR | Finland | |
| Karat | AKT | V2 | Russian Federation | |
| Karibu Airways | Tanzania, United Republic Of | |||
| Karthago Airlines | KAJ | 5R | Tunisia | |
| Kartika Airlines | KAE | Indonesia | ||
| Kavminvodyavia | MVD | KV | Russian Federation | |
| Kazakhstan Airlines | KHN | Kazakhstan | ||
| KBA - Ka'an Beel Air | Mexico | |||
| KD Avia | KNI | KD | KALININGRAD AIR | Russian Federation |
| KEB Aircraft | United States | |||
| Keeler and Tate Management LLC | United States | |||
| Kelowna Flightcraft | Canada | |||
| Kendell Airlines | KDA | KD | Australia | |
| Kenya Airways | KQA | KQ | KENYA | Kenya |
| KevinAir LLC | United States | |||
| Key Airlines | KEY | United States | ||
| Khalifa Airways | KZW | K6 | KHALIFA AIR | Algeria |
| Khalifa Airways Cargo | Algeria | |||
| Kharkov Aircraft Manufacturing Company | WKH | Ukraine | ||
| Khors Aircompany | KHO | X9 | Ukraine | |
| KIL | United States | |||
| King Fung Trading Company Ltd | Unknown | |||
| Kingdom Holding Company | Saudi Arabia | |||
| Kingfisher Airlines | KFR | IT | KINGFISHER | India |
| Kinshasa Airways | KNS | Congo, The Democratic Republic Of The | ||
| Kish Air | IRK | Y9 | Iran, Islamic Republic Of | |
| Kitty Hawk Aircargo | KHA | KR | United States | |
| Kitty Hawk International | CKS | CB | United States | |
| Kiwi International Air Lines | KIA | KP | United States | |
| Kiwi Travel International Airlines | KIC | KC | New Zealand | |
| KLM Alps | LPV | A6 | Austria | |
| KLM Cityhopper | KLC | WA | CITY | Netherlands |
| KLM Exel | AXL | XT | Netherlands | |
| KLM Royal Dutch Airlines | KLM | KL | KLM | Netherlands |
| KLM uk | UKA | UK | United Kingdom | |
| Knights Airlines | KGT | KNIGHT-LINER | Nigeria | |
| Kodiak Associates LLC | United States | |||
| Kokshetau Airline | KRT | Kazakhstan | ||
| Kolavia | KGL | 7K | KOGALYM | Russian Federation |
| KoralBlue Airlines | KBR | K7 | KORAL BLUE | Egypt |
| Korean Air Lines | KAL | KE | KOREANAIR | Korea, Republic Of |
| Korek Airlines | Iraq | |||
| KrasAir | KJC | 7B | Russian Federation | |
| Kulula.com | CAW | MN | South Africa | |
| Kunpeng Airlines | KPA | VD | China | |
| Kurdistan Airlines | Iraq | |||
| Kuwait Air Force | Kuwait | |||
| Kuwait Airways | KAC | KU | Kuwait | |
| Kuzu Airlines Cargo | KZU | GO | KUZU CARGO | Turkey |
| Kyrgyz Air | KAF | KT | Kyrgyzstan | |
| Kyrgyz Airways | KGZ | N5 | BERMET | Kyrgyzstan |
| Kyrgyz International Airlines | KYL | N5 | KYRMAL | Kyrgyzstan |
| Kyrgyzstan Airlines | KGA | R8 | KYRGYZ | Kyrgyzstan |
| Kyrnair | KYN | V4 | France |