| KAY & Shay Property Limited | Real estate | 2021 |
| KAY Controls Limited | Construction | 1997 |
| KAY Freedom Property Ltd | Hospitality | 2024 |
| Kaycee Consult Ltd | Information & communication | 2025 |
| Kayday Limited | Other services | 2020 |
| Kayla Freehold Limited | Households | 2000 |
| Kazoku Martial Arts Essex Ltd | Arts & recreation | 2026 |
| KB Infrastructure Services Limited | Construction | 2021 |
| KBP Transport Limited | Transport & logistics | 2017 |
| KC Collective Ltd | Professional & scientific | 2025 |
| KC Global Consulting Limited | Administrative & support | 2021 |
| KC Power Ltd | Manufacturing | 2022 |
| KC Talents Ltd | Other services | 2022 |
| KCB Associates (Suffolk) Limited | Professional & scientific | 2026 |
| KCS Property Management Limited | Real estate | 2023 |
| KCT Land Ltd | Real estate | 2024 |
| KCW Taverns Limited | Hospitality | 2022 |
| KD Events and Publishing Ltd | Information & communication | 2019 |
| KD Fire Safety Management Limited | Professional & scientific | 2022 |
| KD Supplies Limited | Wholesale & retail | 2017 |
| KDC Consultants Ltd | Administrative & support | 2024 |
| KDN Repair Limited | Wholesale & retail | 2015 |
| KDO Construction Ltd | Construction | 2026 |
| Kean Conveyancing | | 1997 |
| Keane Homes Ltd | Real estate | 2022 |
| KEE Fabrications Ltd | Construction | 2023 |
| KEE Investment Properties Ltd | Real estate | 2023 |
| Keeble Care Ltd | Other services | 2003 |
| Keefe's Properties Ltd | Construction | 2025 |
| Keefes Services Ltd | Construction | 2019 |
| Keep on Swimming Ltd | Arts & recreation | 2019 |
| Keiran Joseph Consulting Ltd | Education | 2025 |
| Kelbrose Limited | Real estate | 2023 |
| Keliso Property Management Limited | Households | 2017 |
| Kelley Property Rentals Ltd | Real estate | 2024 |
| Kelvedon & Feering Cricket Club | Other services | 2008 |
| Kelvedon (Grangewood) Management Company Limited | Households | 2018 |
| Kelvedon Auto Spares 87 Limited | Wholesale & retail | 2018 |
| Kelvedon Barbers Limited | Other services | 2022 |
| Kelvedon Building Contractors Ltd | Construction | 2016 |
| Kelvedon Chef Ltd | Hospitality | 2025 |
| Kelvedon Convenience Store Ltd | Wholesale & retail | 2024 |
| Kelvedon Lawn Mowing Services Ltd | Other services | 2010 |
| Kelvedons Takeaway Ltd | Hospitality | 2025 |
| Kemiveb Ltd | Education | 2023 |
| Kemp Construction Management Limited | Professional & scientific | 2015 |
| Kemps Farm (Holdings) Limited | Real estate | 2018 |
| Kemps Farm Ltd | Professional & scientific | 2024 |
| Kemyas Ltd | Hospitality | 2025 |
| KEN Rush Associates Limited | Professional & scientific | 2005 |
| Kenamchi Limited | Hospitality | 2004 |
| Kendall Facility Management Limited | Construction | 2019 |
| Kendan Group Limited | Information & communication | 2022 |
| Kenjair Limited | Extraterritorial | 2016 |
| Kennedy Animal Welfare Consultancy Limited | Professional & scientific | 2015 |
| Kent Hometec Limited | Construction | 2012 |
| Kent Ridge Investments Ltd | Real estate | 2024 |
| Kentishes Solar Farm 3 Limited | Energy | 2023 |
| Kepler Ventures Ltd | Financial services | 2012 |
| Keres Consulting Ltd | Information & communication | 2016 |
| Kerford Ltd | Manufacturing | 2021 |
| Kern Rentals and Property Limited | Real estate | 2025 |
| Kerr Shearer Limited | Professional & scientific | 2017 |
| Kerrison Land Limited | Administrative & support | 2015 |
| Kestrel Life Sciences Limited | Information & communication | 2013 |
| Keswick (Essex) Ltd | Health & social care | 2017 |
| Ketley Homes Limited | Real estate | 2018 |
| Keto Bite UK Ltd | Hospitality | 2022 |
| Kevi Ltd | Construction | 2023 |
| Kevin Belsham Associates Limited | Administrative & support | 2017 |
| Kevin Dixon Ltd | Professional & scientific | 2020 |
| Kevin FOX Ltd | Construction | 2021 |
| Kevin Helliwell Consultancy Limited | Professional & scientific | 2014 |
| Kevin Knight (Southern) Limited | Construction | 2005 |
| Kevin&Pari-Company Ltd | Hospitality | 2025 |
| KEW Law LLP | | 2009 |
| Key Home Solutions Limited | Financial services | 2012 |
| Key Property Assets Ltd | Construction | 2019 |
| Keyholder Homes Ltd | Extraterritorial | 2006 |
| Keymann Residential Lettings Limited | Households | 2016 |
| Keys Co-Operative Academy Trust | Education | 2017 |
| Keys IS US Ltd | Wholesale & retail | 2012 |
| Keys Retail Limited | Wholesale & retail | 2025 |
| Keysec Services Limited | Administrative & support | 2024 |
| Keysites Limited | Construction | 1998 |
| Keysport Limited | | 1990 |
| Keystone Property London Limited | Construction | 2023 |
| Keystone Stays Limited | Real estate | 2023 |
| Keystone Training and Development Ltd | Education | 2026 |
| Keystone Tyre Ltd | Wholesale & retail | 2025 |
| KFK786 Limited | Hospitality | 2025 |
| KFR Staffing Solutions Ltd | Transport & logistics | 2012 |
| KGH Studios Ltd | Professional & scientific | 2019 |
| Khafo Caring Health Limited | Health & social care | 2025 |
| Khak Ltd | Administrative & support | 2018 |
| Khaliq Trading Ltd | Hospitality | 2024 |
| KHC Civils Limited | Construction | 2025 |
| Khozmo Ltd | Wholesale & retail | 2025 |
| Khushi Health Services Ltd | Health & social care | 2026 |
| Khwaaish Ltd | Wholesale & retail | 2025 |