| Komplex Cyber Consultancy Limited | Information & communication | 2016 |
| Konsilum Ltd | Information & communication | 2022 |
| Korixi Limited | Information & communication | 2011 |
| Koru Coast & Country Homes Limited | Real estate | 2024 |
| Kotte Hamlet 2 Limited | Real estate | 2022 |
| Kotte Hamlet Limited | Real estate | 2022 |
| Kowalski Data Solutions (KDS) Ltd | Information & communication | 2022 |
| KP Carpets & Flooring Ltd | Construction | 2016 |
| KPH Solutions Limited | Information & communication | 2012 |
| KPK Properties Ltd | Real estate | 2024 |
| KPT Freeholds Limited | Real estate | 2009 |
| Kremers Solicitors Limited | Professional & scientific | 2005 |
| KSL Marketing LLP | | 2021 |
| KTW Electrical Ltd | Construction | 2025 |
| Kubedev Ltd | Information & communication | 2017 |
| Kurbside Kravings Limited | Hospitality | 2025 |
| Kurdish MEN Barbers Ltd | Other services | 2023 |
| KV Professional Holdings Limited | Real estate | 2026 |
| KW Design Solutions Limited | Professional & scientific | 2026 |
| Kyctrust Limited | Extraterritorial | 2012 |
| Kynex Limited | Information & communication | 2018 |
| Kynex Telecoms Limited | Information & communication | 2026 |
| Kzam Ltd | Extraterritorial | 2017 |
| L & L Shepherd Holdings Limited | Real estate | 2018 |
| L a Harris Dryliners Ltd | Construction | 2013 |
| L Goodall Property Ltd | Real estate | 2025 |
| L H R J Associates Ltd | Construction | 2013 |
| L I Property Management Ltd | Real estate | 2024 |
| L J Mcnulty & Sons Limited | Administrative & support | 2006 |
| L J S Finishings Limited | Construction | 2016 |
| L Phillips Plastering Limited | Construction | 2022 |
| L W Coatings Ltd | Construction | 2025 |
| L&H Gardening Services Ltd | Administrative & support | 2025 |
| L&J Cleaning Ltd | Administrative & support | 2025 |
| L'Una Design Limited | Other services | 2011 |
| L.A Landscapes Limited | Administrative & support | 2020 |
| L.C.S Smith Holdings Limited | Real estate | 2022 |
| L.I.B Construction Ltd | Construction | 2024 |
| LA Diva Nail & Beauty Limited | Other services | 2026 |
| LA Fenice (Eastleigh) Limited | Hospitality | 2010 |
| LA Sales Recruitment Limited | Administrative & support | 2024 |
| Labcoats and Blackboards Ltd | Professional & scientific | 2025 |
| Labourscope Limited | Construction | 2006 |
| Lacoda Limited | Health & social care | 2011 |
| Ladies of Ledger Ltd | Professional & scientific | 2022 |
| Lady Bettys Drive Whiteley CIC | Households | 2020 |
| LAE Admin Limited | Information & communication | 2023 |
| Laeren Limited | Real estate | 2002 |
| Lagland Street Properties Limited | Construction | 2017 |
| Laidler & Laidler Limited | Manufacturing | 2018 |
| Lake View Care Home Limited | Health & social care | 2025 |
| Lakeside Grays Specsavers Hearcare Limited | Wholesale & retail | 2018 |
| Lakeside Specsavers Limited | Wholesale & retail | 2012 |
| Laly Care Home Ltd | Health & social care | 2024 |
| Lambs Lifts Ltd | Construction | 2024 |
| Lamzomakes Ltd | Manufacturing | 2023 |
| Lana T O'Brien Ltd | Education | 2010 |
| Lanark Specsavers Limited | Wholesale & retail | 1993 |
| Lanark Visionplus Limited | Wholesale & retail | 1993 |
| Lancashire TAR Distillers Limited | Extraterritorial | 1966 |
| Lancaster Specsavers Hearcare Limited | Wholesale & retail | 2007 |
| Lancaster Specsavers Limited | Wholesale & retail | 1989 |
| Lancaster Visionplus Limited | Wholesale & retail | 1993 |
| Lance Consolidation Limited | Financial services | 2020 |
| Lance Holdings Limited | Real estate | 2019 |
| Lance Investments Limited | Financial services | 2019 |
| Lance Mortgages Limited | Financial services | 2021 |
| Lance Property Limited | Real estate | 2021 |
| Lance Property V Limited | Real estate | 2021 |
| Landau (Maritime) Haulage Limited | Manufacturing | 2024 |
| Landau Marine Services Limited | Financial services | 2019 |
| Landau Properties Developments Limited | Construction | 2019 |
| Landau UK Ltd | Manufacturing | 1998 |
| Landaus of London Limited | Real estate | 2017 |
| Landdene Homes Limited | Construction | 2023 |
| Lander Partnership LLP | | 2022 |
| Landkind Ltd | Professional & scientific | 2011 |
| Landlord Guru UK Ltd | Real estate | 2025 |
| Landlord Lettings Ltd | Real estate | 2023 |
| Landmark PI Ltd | Households | 2022 |
| Landwise Homes (Southern) Ltd | Construction | 2025 |
| Landwise Limited | Construction | 2014 |
| Lane Global Limited | Administrative & support | 2001 |
| Laneworth Limited | Hospitality | 2022 |
| Langfell Limited | Construction | 2001 |
| Langham Hall South Limited | Professional & scientific | 2021 |
| Langley Shipping Limited | Other services | 2003 |
| Langley Training Ltd | Education | 2016 |
| Langstone Investments Limited | Professional & scientific | 2000 |
| Lanma Medical Limited | Health & social care | 2022 |
| Lanma Property Limited | Hospitality | 2023 |
| Lansdowne Berkeley Limited | Real estate | 2011 |
| Lanstar Holdings Limited | Professional & scientific | 1990 |
| Lanstar Limited | Water & waste | 1988 |
| Lanstar Pensions Management Limited | Extraterritorial | 1990 |
| Lantheus Biosciences Ltd. | Manufacturing | 2003 |
| Largs Specsavers Limited | Wholesale & retail | 2008 |
| Largs Visionplus Limited | Wholesale & retail | 2008 |
| Larkfield Specsavers Limited | Wholesale & retail | 2018 |
| Larkhall Specsavers Limited | Wholesale & retail | 2017 |