| KIC Projects Ltd | Wholesale & retail | 2010 |
| KID 12 Ltd | Arts & recreation | 2025 |
| Kidaa Limited | Wholesale & retail | 2026 |
| Kidcycle Ltd | Wholesale & retail | 2026 |
| Kids Flourish Zone Ltd | Health & social care | 2021 |
| Kids Properties Ltd | Real estate | 2025 |
| Kidz FUN Place Limited | Wholesale & retail | 2020 |
| Kieron Godby Aesthetics Limited | Other services | 2022 |
| Kikame Limited | Health & social care | 2015 |
| Kilij Digital Ltd | Information & communication | 2026 |
| Killicks Cuisine Ltd | Hospitality | 2018 |
| Kiln Lane Management Limited | Households | 2003 |
| Kiln Road Management Limited | Real estate | 2017 |
| Kiltie Advisory Ltd | Professional & scientific | 2025 |
| Kinau Events Management Ltd | Real estate | 2024 |
| Kind Shine Ltd | Other services | 2023 |
| Kindly Group Ltd | Wholesale & retail | 2026 |
| Kinetic Consultancy Limited | Professional & scientific | 2012 |
| Kinetic Consulting (Europe) Ltd | Professional & scientific | 2022 |
| Kinetic Internet Limited | Information & communication | 2002 |
| Kinetic Therapy Ltd | Other services | 2025 |
| King & Prince Seafood (Europe) Limited | Extraterritorial | 1985 |
| King Community Care Ltd | Health & social care | 2025 |
| King's Chandelier Services Ltd | Wholesale & retail | 2007 |
| King's Chase (Kennett) Management Company Limited | Real estate | 2015 |
| Kingarth Limited | Extraterritorial | 2010 |
| Kingdom Flooring Solutions Limited | Other services | 2019 |
| Kingdom Home Away Stays Ltd | Real estate | 2025 |
| Kingdom Royale Properties Ltd | Real estate | 2025 |
| Kingfisher Bakery Ltd | Wholesale & retail | 2024 |
| Kings Acre (Coggeshall) Management Company Limited | Households | 1995 |
| Kings Meadow (Holt) Management Company Limited | Households | 2017 |
| Kingsford Homes Ltd | Real estate | 2014 |
| Kingsford International Limited | Information & communication | 2005 |
| Kingsland - Bespoke Ltd | Construction | 2024 |
| Kingsland Church Colchester | Other services | 2008 |
| Kingsleigh Residential Limited | Real estate | 2017 |
| Kingsmeadow RTE Company Limited | Households | 2006 |
| Kingsmeadow RTM Company Limited | Households | 2006 |
| Kingston Bishop Limited | Financial services | 2012 |
| Kingswood Accountants Ltd | Professional & scientific | 2020 |
| Kingswood Homes (East Anglia) Limited | Construction | 2005 |
| King’S Landscaping & Services Ltd | Administrative & support | 2024 |
| Kinneret Limited | Professional & scientific | 2012 |
| Kinship in Nature Ltd | Education | 2020 |
| Kinson Tech Ltd | Information & communication | 2025 |
| Kio.Moment Ltd | Wholesale & retail | 2024 |
| KIP Mcgrath Tuition Colchester LP | | 2021 |
| Kirby Locks Limited | Administrative & support | 2002 |
| Kirnad Ltd | Real estate | 2025 |
| Kirni Ltd | Hospitality | 2026 |
| Kirstin Chalmers Ltd | Other services | 2019 |
| Kite Automotive Ltd | Wholesale & retail | 2017 |
| KITE9 Ltd | Information & communication | 2013 |
| Kites Childrens Services Limited | Health & social care | 2000 |
| Kizen Group Ltd | Other services | 2022 |
| KJ Scott Roofing Ltd | Construction | 2021 |
| KJA Rail Solutions Ltd | Construction | 2023 |
| KJB Glazing Installations Ltd | Construction | 2025 |
| Kjpn Accountancy Ltd | Professional & scientific | 2020 |
| Kjpn Consulting Ltd | Professional & scientific | 2026 |
| KK GRP Limited | Hospitality | 2020 |
| KK24/7 Services Ltd | Administrative & support | 2025 |
| KKO Ltd | Wholesale & retail | 2014 |
| KKW Consultancy Limited | Professional & scientific | 2026 |
| Klarenbeek Transport (UK) Ltd | Extraterritorial | 2008 |
| Klarion Ltd | Administrative & support | 2014 |
| Klassywear.Com Limited | Wholesale & retail | 2015 |
| Klatrek Consults Limited | Construction | 2016 |
| KLB Security Ltd | Construction | 2026 |
| Kleantek Services Limited | Administrative & support | 2017 |
| Kleer Solar Ltd | Administrative & support | 2026 |
| Kleos Finance Ltd | Professional & scientific | 2024 |
| Kleroo Limited | Health & social care | 2014 |
| KLK Data Storage Ltd | Information & communication | 2025 |
| KM & SM Properties Ltd | Real estate | 2024 |
| KM Anderson Plumbing & Heating Ltd | Construction | 2023 |
| KMC Autocare Ltd | Wholesale & retail | 2022 |
| KMG Property Solutions Limited | Administrative & support | 2017 |
| KMR Fashion Consultancy Ltd | Wholesale & retail | 2022 |
| KN Hair Salon Limited | Other services | 2025 |
| Knablim Properties Ltd | Real estate | 2018 |
| Kndm Limited | Manufacturing | 2022 |
| Knight Commercial Services Limited | Administrative & support | 1990 |
| Knight Data Limited | Administrative & support | 2016 |
| Knight Pavilion Restaurant Ltd | Hospitality | 2022 |
| Knight Residential Limited | Real estate | 2015 |
| Knight Teknology Ltd | Professional & scientific | 2014 |
| Knightstone Security Ltd | Administrative & support | 2025 |
| KNN International Limited | Wholesale & retail | 2017 |
| Knocck Healthcare Limited | Health & social care | 2022 |
| Knockramer Ltd | Other services | 2013 |
| Know HOW Today Limited | Water & waste | 2018 |
| Knowledge Pathways Intl Limited | Education | 2014 |
| Knowledgeagents Ltd | Professional & scientific | 2012 |
| Knowles Associates Employee Ownership Trustees Limited | Administrative & support | 2020 |
| Knowles Family Investment Company Limited | Financial services | 2023 |
| KNR IT Ltd | Information & communication | 2014 |
| Knss Health Ltd | Health & social care | 2026 |
| KOA RTM Company Limited | Administrative & support | 2009 |