| Kirkmore Ruislip Limited | Real estate | 2024 |
| Kirkmore Securities LLP | | 2005 |
| Kirkmore UE WGC2 Limited | Financial services | 2017 |
| KIT & KIN Ltd | Wholesale & retail | 2015 |
| KIT James Coaching Limited | Professional & scientific | 2018 |
| Kitzbuehel Haven Limited | Real estate | 2008 |
| KJB IT Consultancy Ltd | Information & communication | 2020 |
| KJS Build Ltd | Construction | 2012 |
| Kleancare Cleaning Ltd | Administrative & support | 2025 |
| Klein Bros. (Alexandra) Limited | Real estate | 2022 |
| Klein Bros. (Canonbury) Limited | Real estate | 2021 |
| Klein Bros. (Investments) Limited | Real estate | 1946 |
| Klein Bros. Holdings (Alexandra) Limited | Real estate | 2024 |
| Klein Bros. Holdings (Brighton) Limited | Real estate | 2024 |
| Klein Bros. Holdings (Canonbury) Limited | Real estate | 2024 |
| KMP Global Consultancy Limited | Professional & scientific | 2021 |
| Knights Bespoke Build Limited | Construction | 2021 |
| Knights Oak Limited | Construction | 2014 |
| Koda Auctions Ltd | Real estate | 2025 |
| Koda Estates Ltd | Real estate | 2017 |
| Koda Properties Limited | Real estate | 2016 |
| Koda Property Solutions Limited | Real estate | 2019 |
| Kokosanemi Beaconsfield Limited | Hospitality | 2025 |
| Kollective Technology Limited | Information & communication | 2016 |
| Kolumos Limited | Wholesale & retail | 2010 |
| Konnectnow Ltd | Administrative & support | 2023 |
| Konnetec Group Limited | Other services | 2026 |
| Kora Holdings Limited | Hospitality | 2025 |
| Kpsp Properties Limited | Real estate | 2022 |
| KS 88 Limited | Hospitality | 2026 |
| KS Metrohealth Limited | Administrative & support | 2025 |
| KS Taste Limited | Hospitality | 2024 |
| KS2 Properties Ltd | Real estate | 2020 |
| Kuber AI Ltd | Information & communication | 2025 |
| Kuber Kreate Ltd | Information & communication | 2025 |
| Kudos Blinds Limited | Professional & scientific | 2008 |
| Kunsing 88 Limited | Hospitality | 2025 |
| Kurland Estates Limited | Real estate | 2004 |
| Kwila Associates Limited | Professional & scientific | 2018 |
| Kypo Group Ltd | Wholesale & retail | 2022 |
| Kyriakou Consulting Ltd | Professional & scientific | 2025 |
| L & M Solutions Limited | Professional & scientific | 2013 |
| L S Consulting (Silverstone) Limited | Professional & scientific | 2016 |
| L Training Ltd | Information & communication | 2008 |
| Labyrinth Limited | Construction | 1991 |
| Lacer Properties Ltd | Real estate | 2025 |
| Laesnm Limited | Real estate | 2019 |
| Lakebridge Limited | Information & communication | 2005 |
| Lamden Limited | Information & communication | 2026 |
| Landed Logistics Limited | Transport & logistics | 2026 |
| Landstorm Limited | Professional & scientific | 1993 |
| Lantern House Properties Limited | Real estate | 2017 |
| Lappin Estates Limited | Real estate | 1996 |
| Laroche Leisure Limited | Real estate | 2006 |
| Laserprint Services Limited | Information & communication | 1984 |
| Last Entry Ltd | Information & communication | 2026 |
| Latimer Consulting Group Ltd | Professional & scientific | 2024 |
| Latimer Digital Ltd | Professional & scientific | 2011 |
| Latimer Lettings Ltd | Real estate | 2025 |
| Laurel Co Technology Limited | Manufacturing | 2022 |
| Lavelle Executive Search Limited | Administrative & support | 2018 |
| Lavington Property Ltd | Households | 2025 |
| Law Mind Limited | Education | 2021 |
| LBR Treasury Consulting Limited | Professional & scientific | 2019 |
| LBS Langton Ltd | Construction | 2015 |
| Lcda UK Limited | Financial services | 2015 |
| LDS Property UK Ltd | Real estate | 2021 |
| Ledbb Limited | Other services | 2015 |
| Ledborough Court Holdings Ltd | Households | 2018 |
| Ledborough Holdings Ltd | Financial services | 2018 |
| Legal Advantage Lawyers Limited | Professional & scientific | 2022 |
| Leigh Duncan Law Limited | Professional & scientific | 2016 |
| Leigh Duncan LLP | | 2015 |
| Lemon Studios Associates Ltd | Health & social care | 2017 |
| Lemon WAX Ltd | Information & communication | 2021 |
| Lennard Properties(Sutton)Limited | Real estate | 1955 |
| Lenzburg Holdings Ltd | Financial services | 2023 |
| Leonine Global Developers Limited | Real estate | 2014 |
| Lesa Ltd | Professional & scientific | 2018 |
| Lets Create YOU Ltd | Wholesale & retail | 2021 |
| Levels of Detail Ltd | Professional & scientific | 2020 |
| Lever Geoscience Limited | Professional & scientific | 2018 |
| Levine Dolberg Ltd | Health & social care | 2021 |
| Lewis & Arnold Limited | Construction | 2011 |
| Lewis Group Investments Ltd | Real estate | 2023 |
| Lewis Home Building Ltd | Construction | 2021 |
| Lewis Home Renovation Beaconsfield Ltd | Construction | 2020 |
| Lewis Managing Investments Ltd | Construction | 2021 |
| Lexa Sports Management Limited | Administrative & support | 2013 |
| Libra Mediation Limited | Financial services | 2024 |
| Life in Balance Resources LLP | | 2018 |
| Life Size Holdings Ltd. | Financial services | 2017 |
| Life Size Media Ltd | Professional & scientific | 2010 |
| Life Size Trustees Limited | Administrative & support | 2023 |
| Lifestyle Legal Limited | Professional & scientific | 2015 |
| Lightstart Ltd | Real estate | 2013 |
| Lilhg UK Limited | Hospitality | 2024 |
| Lilliput Vehicle Repairs Limited | Wholesale & retail | 2021 |
| Lily Homes (Home Counties) Ltd | Real estate | 2020 |
| Limelight Health Ltd | Information & communication | 2023 |