| K&N Trans Ltd | Transport & logistics | 2023 |
| K&R&S Limited | Hospitality | 2023 |
| K-Sparks Electrical Services Ltd | Construction | 2012 |
| K. & H. Medical Limited | Construction | 1984 |
| K2 Associates Limited | Manufacturing | 1988 |
| Kabb Global Connect Ltd | Wholesale & retail | 2024 |
| Kaizen Film Ltd | Information & communication | 2024 |
| Kalista Limited | Transport & logistics | 2015 |
| Kallem Investments Ltd | Real estate | 2025 |
| Kamjam Limited | Wholesale & retail | 2021 |
| Kamo River Investments Ltd | Financial services | 2014 |
| Kapil Estates Ltd | Real estate | 2019 |
| Kapsys IT Services Limited | Information & communication | 2026 |
| Kaptan Fish & Chips Ltd | Hospitality | 2025 |
| Karagoz Ltd | Other services | 2018 |
| Karby Michael Ltd. | Energy | 2014 |
| Karnak Gate Developments Ltd | Real estate | 2024 |
| Kasa 4 Limited | Real estate | 2025 |
| Kasa One Limited | Construction | 2024 |
| Kate Butler Counselling Ltd | Health & social care | 2023 |
| Katherine POP Strategy Limited | Administrative & support | 2024 |
| Katie Watkinson Interiors Ltd | Professional & scientific | 2018 |
| Kavi Engineering Limited | Professional & scientific | 2016 |
| Kaymo Ltd | Professional & scientific | 2018 |
| KB Legal Costs Services Ltd | Professional & scientific | 2010 |
| KDL Gore Solutions Ltd | Professional & scientific | 2016 |
| Keating Project Management Limited | Administrative & support | 2020 |
| KEE Locksmith Ltd | Construction | 2018 |
| Keetley Studio Ltd | Professional & scientific | 2025 |
| Kelgrove Wells Limited | Construction | 1980 |
| Kelph Limited | Construction | 2022 |
| Kempton Financial Solutions Limited | Professional & scientific | 2016 |
| Kenny Property Limited | Real estate | 2025 |
| Kenworthy & Co Vintage Motor Works Limited | Wholesale & retail | 2013 |
| Kerb Consultancy Ltd | Professional & scientific | 2021 |
| KES Histopathology Ltd | Health & social care | 2024 |
| Keygrove Logistics Limited | Transport & logistics | 2001 |
| Keys & LEE (Financial Services) Limited | Real estate | 1987 |
| Kiason Global Ltd | Professional & scientific | 2020 |
| Kidd Scaffolding Limited | Construction | 2009 |
| Kikori Ltd | Agriculture & fishing | 2021 |
| Kinen UK Limited | Manufacturing | 2020 |
| Kingfisher Construction (2008) Limited | Construction | 2012 |
| Kingsgate Property Investments Ltd | Real estate | 2015 |
| Kingston Land Limited | Construction | 2025 |
| Kinthistle Limited | Professional & scientific | 2016 |
| Kionlough Investments Limited | Real estate | 2008 |
| Kirtland Homes Limited | Construction | 2021 |
| Kittiwake Digital Limited | Information & communication | 2024 |
| KLS Corton Holidays Limited | Hospitality | 2015 |
| Klsf Limited | Information & communication | 2024 |
| KM New Power Ltd | Construction | 2025 |
| KMA Carpentry Limited | Construction | 2025 |
| KMP Create Ltd | Information & communication | 2016 |
| Knights Removals Ltd | Transport & logistics | 2026 |
| KNN White Ltd | Professional & scientific | 2025 |
| Knowledgeworks Intranet Limited | Information & communication | 1997 |
| KO Plant Operators Ltd | Water & waste | 2024 |
| Kogane AI Limited | Information & communication | 2026 |
| Kokobrasserie Limited | Financial services | 2023 |
| Kondor Express Services Ltd | Wholesale & retail | 2024 |
| Konrad Frost Limited | Information & communication | 2017 |
| Kotcars Ltd | Wholesale & retail | 2020 |
| KPG74 Limited | Professional & scientific | 2015 |
| Kplane MEP Services Ltd | Professional & scientific | 2025 |
| KPW HR Consulting Limited | Administrative & support | 2011 |
| KR Photo Services Limited | Information & communication | 2011 |
| KRB Enterprises Limited | Professional & scientific | 2008 |
| Kris Fit PT Limited | Arts & recreation | 2018 |
| Kristad Limited | Health & social care | 2014 |
| KRS Bishops Stortford Limited | Hospitality | 2024 |
| KRS Great Dunmow Limited | Hospitality | 2024 |
| KS Property Development Ltd | Real estate | 2026 |
| KTB Properties Limited | Real estate | 2018 |
| KVA Maddison Consultancy Limited | Professional & scientific | 2024 |
| Kvdp Developments Limited | Construction | 2018 |
| Kwari UK Limited | Information & communication | 2016 |
| KWL Groundworks Ltd | Construction | 2026 |
| Kwoon Ltd | Extraterritorial | 2019 |
| Kyproulla Pierides Ltd | Wholesale & retail | 2024 |
| L & T Factoring Services Ltd. | Financial services | 2017 |
| L B-Wilson Services Limited | Professional & scientific | 2025 |
| L Edmonds Design Consultancy Ltd | Wholesale & retail | 2014 |
| L J SEE Consulting Limited | Professional & scientific | 2018 |
| L Lake Holdings Ltd | Financial services | 2026 |
| L&Gjm Limited | Hospitality | 2020 |
| L&J Invest Limited | Arts & recreation | 2025 |
| L&T Accounting Services Ltd. | Professional & scientific | 2014 |
| L.A.B. Facilities Management Limited | Administrative & support | 2018 |
| LA Levade Limited | Agriculture & fishing | 2015 |
| LA Vita Coffee Hub Limited | Hospitality | 2014 |
| Labby Green Close Management Company Limited | Households | 2020 |
| LAC Projects Limited | Administrative & support | 2026 |
| Laguna Developments Limited | Real estate | 2021 |
| Laguna INV Ltd | Wholesale & retail | 2023 |
| Laguna Rentals Limited | Real estate | 2022 |
| Laina (PVT) Ltd | Administrative & support | 2025 |
| Laings Developments Ltd | Construction | 2026 |
| Lala Inn Ltd | Hospitality | 2026 |
| Lalae Ltd | Financial services | 2024 |