| Klaidi Property Group Ltd | Real estate | 2025 |
| Klair Health Limited | Health & social care | 2025 |
| Klassique Services Ltd | Health & social care | 2026 |
| Klix (Hair & Nails) Limited | Other services | 2006 |
| Klondon Connections Limited | Professional & scientific | 2003 |
| Klyropro Ltd | Information & communication | 2025 |
| KMB Enterprise Limited | Information & communication | 1995 |
| KMF Assets Limited | Real estate | 2021 |
| KMS Design Limited | Professional & scientific | 2000 |
| Knauf Jewels Ltd | Wholesale & retail | 2016 |
| KNF Electrical Contractors Limited | Construction | 2003 |
| Knight & Co Accountants Limited | Professional & scientific | 2007 |
| Knight Wheeler Limited | Professional & scientific | 2002 |
| Knighton Associates Ltd | Professional & scientific | 2026 |
| Knights Security Services Ltd | Administrative & support | 2020 |
| Knightsbridge Cleaning Services Limited | Administrative & support | 2007 |
| Knightsbridge Commercial Investments Limited | Real estate | 2022 |
| Knightwood Studio Ltd | Manufacturing | 2026 |
| Knotted Roots Ecology and Tree Care Ltd | Professional & scientific | 2026 |
| Kofto Ltd | Information & communication | 2014 |
| KOJ Care Solutions Limited | Health & social care | 2026 |
| Kojin Clothing Ltd | Wholesale & retail | 2023 |
| Kolcz Ltd | Wholesale & retail | 2026 |
| Konmat Ltd | Wholesale & retail | 2026 |
| Konnect Media Group Ltd | Professional & scientific | 2025 |
| Kontegent 2026 Ltd | Information & communication | 2026 |
| Kornerway Ltd | Wholesale & retail | 2020 |
| Kosass Care Ltd | Wholesale & retail | 2025 |
| Kovalov Services Limited | Construction | 2018 |
| KPI Software Limited | Information & communication | 2021 |
| KR Capital Properties Ltd | Real estate | 2025 |
| Krepz Ltd | Financial services | 2026 |
| Krijudino Ltd | Information & communication | 2025 |
| Krovia Limited | Wholesale & retail | 2026 |
| KS Logistics Solutions Limited | Transport & logistics | 2025 |
| KSA Fish & Chips Limited | Real estate | 2015 |
| KSS Diamond Drilling and Sawing Limited | Construction | 1997 |
| KSS Hire Services Limited | Administrative & support | 1995 |
| KST Accountants Limited | Professional & scientific | 2025 |
| KSV Group Limited | Wholesale & retail | 2025 |
| Kubelink Limited | Hospitality | 2017 |
| Kubeth Live Stores Ltd | Arts & recreation | 2025 |
| Kuga Property Ltd | Real estate | 2025 |
| Kuiz Ltd | Wholesale & retail | 2025 |
| Kumar International Films Limited | Information & communication | 2022 |
| Kung FU Ltd | Information & communication | 2001 |
| Kuppackal Sons Ltd | Construction | 2024 |
| Kurby Driving School Ltd | Education | 2024 |
| Kurdish UK Visa & Immigration Ltd | Professional & scientific | 2022 |
| Kwame Sarpongasiedu Ltd | Professional & scientific | 2012 |
| Kwest Telecom Limited | Information & communication | 2023 |
| Kwik Contracts Limited | | 2003 |
| Kyerlyn Ltd | Wholesale & retail | 2024 |
| Kynectom Limited | Wholesale & retail | 2025 |
| Kyzo.Fire Ltd | Wholesale & retail | 2026 |
| KZ Accurate Accountants Ltd | Professional & scientific | 2025 |
| K`S Bathroom & Kitchen Centre Limited | Wholesale & retail | 2003 |
| L & S Joinery Limited | Manufacturing | 2007 |
| L C Pearl Limited | Administrative & support | 2022 |
| L D Robins Decorating Limited | Construction | 2003 |
| L Galpin & SON Electrical Limited | Construction | 2006 |
| L J Intervention Limited | Health & social care | 2004 |
| L&J Digital Solutions LLP | | 2026 |
| L. Holmes Dental Laboratory Ltd | Health & social care | 2002 |
| L.E. Brand & Sons Limited | Other services | 1991 |
| L.F.King & SON Limited | Construction | 1958 |
| L.G.Goodwin Limited | Real estate | 1952 |
| L.J. Flower Limited | Agriculture & fishing | 1983 |
| L.M. Installations Limited | Construction | 1990 |
| LA Consultancy Services Limited | Professional & scientific | 1997 |
| LA Dolce 85 Ltd | Hospitality | 2024 |
| LA Global Healthcare Ltd | Health & social care | 2023 |
| LA Piazza Limited | Hospitality | 2003 |
| LA Princesse Ltd | Manufacturing | 2012 |
| LA Qrue Ltd | Financial services | 2023 |
| LA Rossella Limited | Hospitality | 2011 |
| LA Stretch Limo's Limited | Transport & logistics | 1998 |
| Labourbaseuk Executive Search Ltd | Administrative & support | 2022 |
| LAC Traders Ltd | Wholesale & retail | 2025 |
| Ladywell Limited | Real estate | 1981 |
| Lagozi Limited | Health & social care | 2025 |
| LAI Aquatics International Ltd | Wholesale & retail | 2008 |
| Laindon Car Centre Services Limited | Wholesale & retail | 2007 |
| Laindon Tyre Centre Limited | Administrative & support | 2007 |
| Lakemoor Limited | Real estate | 2000 |
| Lakemore Construction Ltd | Wholesale & retail | 2006 |
| Lakeside Karting Limited | Arts & recreation | 1998 |
| Lakeside Medical Services Ltd | Health & social care | 2024 |
| Lakewells Limited | Wholesale & retail | 1988 |
| Lakuben Medical Limited | Health & social care | 2024 |
| LAL Trading Company (London) Limited | | 1968 |
| Lalabazar Spice Ltd | Hospitality | 2022 |
| Lamakazi Union Welfare Association UK Ltd | Health & social care | 2023 |
| Lana Ventures Ltd | Financial services | 2025 |
| Land Finance & Mortgage Corporation Limited(The) | Real estate | 1933 |
| Land Management Limited | Real estate | 1922 |
| Landmark Housing Group Limited | Hospitality | 2002 |
| Landmark Motor Group Ltd | Wholesale & retail | 2019 |
| Lanroy Limited | Information & communication | 2015 |
| Lapwing Hospitality Ltd | Other services | 2019 |