| 701 | KC | Air Astana | ICAO: KZR, Callsign: Astanaline, IATA Prefix: 465, IATA designator changed from 4L w.e.f. 29 October 2006. ICAO designator changed from AST. IATA Designator changed from LQ* | KZ | AVCODES |
| 702 | KC | The Kanawha Central Ry. Co. | 1/1975 | | NAKINA |
| 703 | KC | The Kanawha Central Ry. Co. | Jan-75 | | NRHS |
| 704 | KC | KANAWHA CENTRAL RAILROAD CO. | | | PWRC |
| 705 | KC | KOLEJE CZESKIE Sp. z o.o. | | PL | VKM |
| 706 | KCA | Trans-Kiev | Callsign: Trans-Kiev, Name changed to Aviatrans K Ltd, Air Company. | UA | AVCODES |
| 707 | KCA | Chosonmihang CAA of DPR of Korea | IATA: JS, Callsign: Juliett Sierra, ICAO designator changed frm CSM | PRK | AVCODES |
| 708 | KCA | Chosonmihang CAA of DPR of Korea | IATA: JS, Callsign: Air Korea, Name changed to Air Koryo. ICAO designator changed frm CSM | PRK | AVCODES |
| 709 | KCA | Aviatrans K Ltd, Air Company | IATA: KI, Callsign: Trans Kiev, Name changed from Trans-Kiev. | UA | AVCODES |
| 710 | KCA | Trans-Kiev | | | ICAO1 |
| 711 | KCAC | K-C AND COMPANY TRUCKING | | | SCAC3 |
| 712 | KCAG | KEANS CARTAGE INC | | | SCAC3 |
| 713 | KCAIRPORT | Kansas City International Airport | | USA | TRAFFIC |
| 714 | KCAP | KOENIGS CUSTOM APPLICATION | | | SCAC4 |
| 715 | KCAR | KAIM CARRIERS | | | SCAC4 |
| 716 | KCAS | K C & SON TOOL & EQUIPMENT RENTAL | | | SCAC3 |
| 717 | KCAS | KANZA COOPERATIVE ASSOCIATION | | | SCAC4 |
| 718 | KCATA | Kansas City Area Transportation Authority | | USA | TRAFFIC |
| 719 | KCAX | KCAC, Inc. | added 10/1985; eliminated 1/1987 | | NAKINA |
| 720 | KCAX | KCAC, Inc. | eliminated 1/87 | | NRHS |
| 721 | KCAX | KCAC INC. | | | PWRC |
| 722 | KCBU | IMOTO LINES, LTD. | | J | BIC |
| 723 | KCBU | SUMISHO GLOBAL LOGISTICS CO LTD | | | SCAC4 |
| 724 | KCBX | KCBX TERMINALS CO. | | | PWRC |
| 725 | KCC | Kansas City Connecting R.R. Co. | 1/1975-1/1980 | | NAKINA |
| 726 | KCC | Kansas City Connecting R.R. Co. | 1/75-1/80 | | NRHS |
| 727 | KCC | KANSAS CITY CONNECTING RAILROAD CO. | | | PWRC |
| 728 | KCCI | K C CARTAGE INC | | | SCAC3 |
| 729 | KCCI | K C TRANSPORTATION INC | | | SCAC4 |
| 730 | KCCL | KCC TRANSPORT SYSTEMS INC | | | SCAC3 |
| 731 | KCCL | KCC TRANSPORT SYSTEMS INC | | | SCAC4 |
| 732 | KCCN | KUNSHEK CHAT & COAL INC | | | SCAC3 |
| 733 | KCCP | KINDER CARTAGE CORP | | | SCAC3 |
| 734 | KCCP | K C COMPANY | | | SCAC4 |
| 735 | KCCQ | KANSAS CITY COMMERCIAL CARTAGE CO I | | | SCAC3 |
| 736 | KCCQ | K & C CONTRACTORS INC | | | SCAC4 |
| 737 | KCCS | KANSAS CITY COLD STORAGE & ICE | | | SCAC4 |
| 738 | KCCX | Kennecott Utah Copper Corp. | added 4/1991; 1/1994-7/2005 | | NAKINA |
| 739 | KCCX | Kennecott Corp. | added 4/1981; eliminated 4/1991 | | NAKINA |
| 740 | KCCX | Kennecott Copper Corp. | added 4/1970; 4/1970-1/1980; eliminated 4/1981 | | NAKINA |
| 741 | KCCX | Kimberly-Clark Co. | 7/1937-4/1961 | | NAKINA |
| 742 | KCCX | Kimberly-Clark Corp. | 7/1930-7/1935 | | NAKINA |
| 743 | KCCX | Kimberly-Clark Co. | 4/38-4/61 | | NRHS |
| 744 | KCCX | Kennecott Copper Corp. | added 4/70; 4/70-1/80; eliminated 4/81 | | NRHS |
| 745 | KCCX | Kennecott Corp. | added 4/81; eliminated 4/91 | | NRHS |
| 746 | KCCX | Kennecott Utah Copper Corp. | added 4/91; 1/94-7/2000 | | NRHS |
| 747 | KCCX | *KIMBERLY-CLARK CO. | | | PWRC |
| 748 | KCCX | +KENNECOTT UTAH COPPER CORPORATION | | | PWRC |
| 749 | KCCX | Kennecott Utah Copper Corporation | | | RSRV |
| 750 | KCCX | KENNECOTT UTAH COPPER CORPORATION | | | SCAC4 |
| 751 | KCCX | Kennecott Copper Corp. | | USA | TRAFFIC |
| 752 | KCCY | KDC CONSTRUCTION COMPANY | | | SCAC4 |
| 753 | KCCZ | KAISER CEMENT COMPANY | | | PWRC |
| 754 | KCDC | KRAFT FOODSERVICE INC | | | SCAC3 |
| 755 | KCDI | KUTCHIN OF CANADA INC | | | SCAC4 |
| 756 | KCDL | K C DEDICATED LLC | | | SCAC4 |
| 757 | KCDS | KATIE COURIER & DELIVERY SERVICE IN | | | SCAC4 |
| 758 | KCDT | KCD TRANSPORT | | | SCAC3 |
| 759 | KCDU | KALYPSO COMPAGNIA DI NAVIGAZIONE SPA | | I | BIC |
| 760 | KCDU | KALI-CHEMIE A.G. | | | SCAC3 |
| 761 | KCDX | Eastman Kodak Co. | added 1/1976; 1/1980-7/2000; eliminated 7/2005; 7/2005 (not listed) | | NAKINA |
| 762 | KCDX | Eastman Kodak Co. | 1/80-7/2000 | | NRHS |
| 763 | KCDX | EASTMAN KODAK CO | | | PWRC |
| 764 | KCDX | Eastman Kodak | | | RSRV |
| 765 | KCE | K C Piper Sales, Inc. | Callsign: KayCee, | USA | AVCODES |
| 766 | KCE | Irving Oil Transport Ltd. | Callsign: Kacey, | CDN | AVCODES |
| 767 | KCE | Irving Oil Transport | | | ICAO1 |
| 768 | KCEI | KIFF, C E INC | | | SCAC4 |
| 769 | KCEM | KCE INC | | | SCAC4 |
| 770 | KCEN | KRAMER-CAS | | | SCAC4 |
| 771 | KCEP | KC EXPRESS INC | | | SCAC3 |
| 772 | KCES | KC EXPRESS (KC FREIGHT SYSTEMS INC | | | SCAC3 |
| 773 | KCEX | Kazco Enterprises, Inc. | 7/2005 (not listed) | | NAKINA |
| 774 | KCEX | KAZCO ENTERPRISES, INC. | | | PWRC |
| 775 | KCEX | KAZCO ENTERPRISES INC | | | SCAC4 |
| 776 | KCFI | K C FORWARDING INC | | | SCAC3 |
| 777 | KCFQ | KEPPLER, CHARLES F | | | SCAC3 |
| 778 | KCFT | KCF TRANSPORTATION | | | SCAC4 |
| 779 | KCGF | K C GIFTS | | | SCAC4 |
| 780 | KCGM | K.C.G.M. TRANSPORT | | | SCAC3 |
| 781 | KCGM | K C G M TRANSPORT | | | SCAC4 |
| 782 | KCGO | KEEN COMPRESSED GAS CO | | | SCAC4 |
| 783 | KCGT | KCG TRANSPORT LLC | | | SCAC4 |
| 784 | KCGX | Cemex, Inc. | added 7/2005; 7/2005 | | NAKINA |
| 785 | KCGX | Southdown, Inc. | added 1/1997; eliminated 7/1997; 7/2000 (not listed) | | NAKINA |
| 786 | KCGX | Mitsubishi Cement Corp. | added 1/1990; 1/1994; eliminated 1/1997 | | NAKINA |
| 787 | KCGX | Kaiser Cement Corp. | added 1/1980; 1/1980; eliminated 1/1990 | | NAKINA |
| 788 | KCGX | Kaiser Cement & Gypsum Corp. | added 10/1965; 10/1966-1/1975; eliminated 1/1980 | | NAKINA |
| 789 | KCGX | Kaiser Cement & Gypsum Corp. | added 10/65; 10/66-1/75; eliminated 1/80 | | NRHS |
| 790 | KCGX | Kaiser Cement Corp. | added 1/80; 1/80; eliminated 1/90 | | NRHS |
| 791 | KCGX | Mitsubishi Cement Corp. | added 1/90; 1/94; eliminated 1/97 | | NRHS |
| 792 | KCGX | Southdown, Inc. | added 1/97; eliminated 7/97; 7/2000 | | NRHS |
| 793 | KCGX | *MITSUBISHI CEMENT CORPORATION [KAISER CEMENT CORP.] | | | PWRC |
| 794 | KCGX | *SOUTHDOWN INCORPORATED | | | PWRC |
| 795 | KCGX | +CEMEX, INC. | | | PWRC |
| 796 | KCGX | Kaiser Cement Corporation (Southdown) | | | RSRV |
| 797 | KCGX | KAISER CEMENT & GYPSUM CORP | | | SCAC3 |
| 798 | KCGX | CEMEX INC | | | SCAC4 |
| 799 | KCH | KC International Airlines Co., Ltd. d/b/a KC International Airlines | IATA: 3Q, Callsign: Cam Air, Due to commence in 2018 | K | AVCODES |
| 800 | KCHC | KOCH CARBON LLC | | | SCAC4 |
