| KCC Electrical Ltd | Construction | 2016 |
| KCK Engineering Services Limited | Administrative & support | 2015 |
| KCM Advisory Limited | Financial services | 2022 |
| KCP Developments Limited | Real estate | 2002 |
| KCP International Ltd | Financial services | 2009 |
| Kdfm Limited | Transport & logistics | 2019 |
| KDJ Beauty House Ltd | Other services | 2026 |
| KDK Fire Protection Ltd | Construction | 2019 |
| KE Consulting Limited | Other services | 2015 |
| Kebble Environmental Services Limited | Administrative & support | 2003 |
| Kebble Holdings Limited | Financial services | 2025 |
| Keenan Roofing Limited | Construction | 2017 |
| Keep Consulting Limited | Professional & scientific | 2007 |
| Keep Investments Limited | Real estate | 2022 |
| Keep IT 100 Youth CIC | Other services | 2020 |
| Keh’S Enterprise Ltd | Wholesale & retail | 2023 |
| Keilkraft Services Limited | Education | 2022 |
| Keith Ashton Estates Limited | Real estate | 2002 |
| Keith Ashton Ltd | Real estate | 2013 |
| Keith James Agencies Limited | Professional & scientific | 1982 |
| KEL553Y Ltd | Real estate | 2022 |
| Kela Property Services Ltd | Construction | 2014 |
| Kellion Private Clients Limited | Real estate | 2025 |
| Kellman Consultants Limited | Administrative & support | 2026 |
| Kelly Anne Stringer Limited | Extraterritorial | 2023 |
| Kelly Beagle Nutrition Ltd | Health & social care | 2025 |
| Kelly Family Law Limited | Professional & scientific | 2020 |
| Kelly Louise Clark Limited | Information & communication | 2014 |
| Kelly's Building Ltd | Construction | 2020 |
| Kellybronze Limited | Professional & scientific | 1999 |
| Kellybronze Scotland Limited | Agriculture & fishing | 1997 |
| Kelmscott House (Freehold) Limited | Real estate | 2013 |
| Kelsey Electrical Limited | Construction | 2014 |
| Kelson Building Services Limited | Construction | 2013 |
| Kelvedon FOX Properties Limited | Real estate | 2019 |
| Kelvelec Electrical Supplies Ltd | Wholesale & retail | 2003 |
| Kemansons Ltd | Wholesale & retail | 2022 |
| Kempton Builders Limited | Construction | 2016 |
| Kemsley LLP | | 2007 |
| KEN Judge & Associates Limited | Other services | 1990 |
| Kendall Development Solutions Ltd | Professional & scientific | 2015 |
| Kendo Contracts Limited | Professional & scientific | 2005 |
| Kendrick Independent Social Worker Ltd | Health & social care | 2012 |
| Kennedy Homes (Essex) Ltd | Households | 2025 |
| Kenny & Harvey Limited | Professional & scientific | 2011 |
| Kenrick Flat Management Company Limited | Households | 1981 |
| Kent Property Renovation Services Limited | Construction | 2018 |
| Kent Spedition Limited | Professional & scientific | 1982 |
| Kent Witham Contracts Limited | Construction | 2003 |
| Kentech Technical Services Limited | Information & communication | 2016 |
| Kentlincs Fire and Facilities Limited | Construction | 2009 |
| Kentlincs Limited | Extraterritorial | 2014 |
| Kentlincs Response Limited | Administrative & support | 2014 |
| Kepajo Investments Limited | Real estate | 2002 |
| Kepi 75 Ltd | Transport & logistics | 2011 |
| Keppel Bay Limited | Real estate | 2024 |
| Kerina Engineering Limited | Professional & scientific | 2015 |
| Kershon Limited | Information & communication | 2002 |
| Kesara Jewellery Ltd | Wholesale & retail | 2026 |
| Kestrel Carpentry Ltd | Construction | 2013 |
| Kestrel Maintenance Limited | Construction | 2009 |
| Ketley Consultancy Services Ltd | Professional & scientific | 2018 |
| Ketray Contract Cleaning Limited | Administrative & support | 1997 |
| Kevin Downey Associates Ltd | Professional & scientific | 2009 |
| Key Largo Holdings Limited | Financial services | 2024 |
| Keydom Games Limited | Wholesale & retail | 2020 |
| Keyne Leisure Limited | Arts & recreation | 2016 |
| Keyser Homes Ltd | Real estate | 2021 |
| Keystone Cleaning Specialists Ltd | Administrative & support | 2026 |
| Keystone Developments (South West) Ltd | Construction | 2020 |
| Keystone Property Development and Lettings Limited | Real estate | 2025 |
| Keystone Surveying Services Ltd | Professional & scientific | 2019 |
| Keystone Vertex Property Limited | Real estate | 2024 |
| Kezie Consulting Ltd | Professional & scientific | 2012 |
| KFB Enterprises Ltd | Real estate | 2019 |
| KG Smiles Ltd | Health & social care | 2018 |
| KGA Marketing Ltd | Professional & scientific | 2025 |
| KH (CRM) Limited | Professional & scientific | 2016 |
| KH Renovate Limited | Real estate | 2024 |
| Khalil CH Limited | Health & social care | 2022 |
| Khan Thornton Limited | Professional & scientific | 2020 |
| Khanya Care Consultancy Limited | Health & social care | 2020 |
| KI BIO Ltd | Wholesale & retail | 2026 |
| Kibblewhite Property Group Limited | Professional & scientific | 2023 |
| Kido's Pantry Ltd | Manufacturing | 2024 |
| Kids Inspire | Health & social care | 2007 |
| Kids Play Village Ltd | Arts & recreation | 2023 |
| Kigo Limited | Information & communication | 2025 |
| Kiku Trading Limited | Professional & scientific | 2012 |
| Kilburn Capital Consultancy Limited | Professional & scientific | 2026 |
| Kiln and Lodge Estates Ltd | Real estate | 2021 |
| Kilo Cars (Essex) Limited | Transport & logistics | 2011 |
| Kilo Cars Limited | Transport & logistics | 1973 |
| Kimberley Chambers Limited | Information & communication | 2010 |
| Kimchique Ltd | Hospitality | 2026 |
| Kims Thai Kitchen Ltd | Hospitality | 2026 |
| Kindred Calm Ltd | Wholesale & retail | 2025 |
| King Carbon Performance Parts Ltd | Manufacturing | 2023 |
| King Edward VI Grammar School, Chelmsford | Education | 2011 |
| King Electrical and Maintenance Services Limited | Construction | 2024 |