| Just Loveleigh Boutique Hair and Beauty Limited | Other services | 2022 |
| Justinsaundersdev Ltd | Information & communication | 2022 |
| JVR Solutions Limited | Information & communication | 2026 |
| JW Holdings (Contracts) Ltd | Financial services | 2023 |
| JWC Law LLP | | 2020 |
| JZR Limited | Real estate | 2019 |
| K & G Property Ltd | Real estate | 2017 |
| K & H Fast Fit Ltd | Wholesale & retail | 2022 |
| K & H Tyres & Servicing Ltd | Wholesale & retail | 2019 |
| K Baxter Consultancy Limited | Manufacturing | 2011 |
| K D S Building Contractors Ltd | Construction | 2023 |
| K M 8 Limited | Professional & scientific | 2024 |
| K Morris Properties (Essex) Ltd | Real estate | 2024 |
| K Nine Corporations Limited | Other services | 2019 |
| K One Barbers Limited | Other services | 2002 |
| K&K Floors and Blinds Ltd | Wholesale & retail | 2024 |
| K-Berg Property Limited | Real estate | 2022 |
| K-Pop in Ltd | Wholesale & retail | 2025 |
| K. C. Business Consultancy Limited | Financial services | 2006 |
| K. D. Burns Limited | Professional & scientific | 2009 |
| K.A.S.Property Services Limited | Real estate | 2006 |
| K.C.P. Demolition Limited | Construction | 1994 |
| K.D Leach Limited | Construction | 2009 |
| K2 Commercial Management Limited | Professional & scientific | 2003 |
| Kaelectricalsolutions Ltd | Administrative & support | 2017 |
| Kafer Ltd | Construction | 2016 |
| Kahve Engineering & Design Limited | Professional & scientific | 2012 |
| Kalagra Limited | Agriculture & fishing | 2016 |
| Kamala-Krishna Medical Services Limited | Health & social care | 2013 |
| Kamboj Properties Ltd | Real estate | 2021 |
| Kamonet Ltd | Manufacturing | 2020 |
| Kampag Limited | Information & communication | 2006 |
| Kandola & Sons Ltd | Real estate | 2020 |
| Kandola Brothers Limited | Real estate | 2021 |
| Kandola Homes Limited | Real estate | 2016 |
| Kandola Investments Ltd | Real estate | 2016 |
| Kane UK Holdings Limited | Financial services | 2025 |
| Kaning Productions Limited | Other services | 2013 |
| Kapc Ltd | Information & communication | 2020 |
| Kaptix Limited | Wholesale & retail | 2025 |
| Karen Harvey-Conran Training Limited | Other services | 2024 |
| Karmann Konnection Limited | Wholesale & retail | 2025 |
| Karrica Ltd | Real estate | 2025 |
| Kaspas Gloucester Ltd | Hospitality | 2015 |
| Kathryn Knight Limited | Information & communication | 2006 |
| Katia Design Limited | Administrative & support | 1994 |
| Katie Durham Resourcing Limited | Administrative & support | 2024 |
| Kauto Ltd | Professional & scientific | 2009 |
| KAV Trading Limited | Wholesale & retail | 2014 |
| KB Commercial Painters Ltd | Construction | 2022 |
| KC1 Group Ltd | Construction | 2019 |
| KCA Accountants Limited | Professional & scientific | 2012 |
| KCP Recruitment Limited | Administrative & support | 2020 |
| Kebab Leigh on Sea Ltd | Hospitality | 2026 |
| Kebabs R US Limited | Hospitality | 2017 |
| Keep Cool Air Conditioning Limited | Construction | 2025 |
| Keep ME Posted VA Ltd | Administrative & support | 2021 |
| Keepcity Limited | Real estate | 1990 |
| Kelgra Cleaning Services Ltd | Administrative & support | 2018 |
| Kellie Samuda Private Travel Consultancy Ltd | Administrative & support | 2024 |
| Kelvedon House Management Limited | Households | 2019 |
| Kemp's Castles Ltd | Manufacturing | 2021 |
| Kendal Way Limited | Real estate | 2017 |
| Kendo Nagasaki Holdings Ltd | Real estate | 2025 |
| Kenneth Robin Properties Ltd | Real estate | 2021 |
| Kensington Roofing & Building Limited | Construction | 2025 |
| Kent Builders Ltd | Construction | 2022 |
| Kent Haulage & Construction Ltd | Water & waste | 2015 |
| Kent Horizons Ltd | Real estate | 2020 |
| Kent Palette & Pixel Ltd | Administrative & support | 2025 |
| Kent Ultimate Cars Ltd | Wholesale & retail | 2022 |
| Kents Landscape&Development Limited | Construction | 2022 |
| KES Capital Ltd | Professional & scientific | 2016 |
| Kevin Bowes Carpentry Limited | Other services | 2010 |
| Key Diligence Ltd | Information & communication | 2025 |
| Key Time Management Solutions Ltd | Administrative & support | 2001 |
| Keys to the PAD Limited | Real estate | 2025 |
| Keyston Group Limited | Construction | 2018 |
| Keystone & Knoll Ltd | Real estate | 2026 |
| Keystone Tonewoods Limited | Other services | 2009 |
| KG Electrical Contractors Ltd | Construction | 2019 |
| KGB Design and Print Ltd | Professional & scientific | 2018 |
| KGW Flooring Ltd | Construction | 2026 |
| KH Bradwell on Sea Limited | Hospitality | 2026 |
| Khan Property Holdings Ltd | Real estate | 2024 |
| Kiafield Developments Limited | Real estate | 1992 |
| Kiaros Place Ltd | Health & social care | 2018 |
| Kick OFF Physical Activity Ltd | Arts & recreation | 2019 |
| Kids Kingdom Southend Limited | Arts & recreation | 2013 |
| Kidz Camp Essex Ltd | Health & social care | 2016 |
| Kieran's Sport Therapy Limited | Other services | 2022 |
| Kikin SPV Limited | Financial services | 2025 |
| Kilham Farr Ltd | Professional & scientific | 2021 |
| Kilic Hairdresser Limited | Other services | 2021 |
| Kilkies Holdings Limited | Hospitality | 2020 |
| Killa Cosmetics Academy Ltd | Other services | 2023 |
| Killa Cosmetics Ltd | Other services | 2023 |
| Kimbo Design Limited | Professional & scientific | 2015 |
| Kinetic Contracts Ltd | Construction | 2015 |
| Kinetic Kids Academy Limited | Arts & recreation | 2017 |