| Kingstable Street Estate RES. (Eton) Limited | Households | 1994 |
| Kinxias Ltd | Wholesale & retail | 2023 |
| Kirkman Productions Ltd | Information & communication | 2015 |
| KIS Associates Limited | Administrative & support | 2019 |
| KIT Cube Ltd | Wholesale & retail | 2023 |
| Kite Consulting Services Ltd | Professional & scientific | 2016 |
| KJ Build and Design Limited | Construction | 2021 |
| KK Associates Services Ltd | Health & social care | 2023 |
| Klass Mercedes Limited | Transport & logistics | 2026 |
| Klintec Ltd. | Hospitality | 2013 |
| Klosi Express Ltd | Transport & logistics | 2019 |
| KLW Preschool Limited | Education | 2023 |
| KMC Venture Ltd | Construction | 2014 |
| KND Investments Limited | Financial services | 2019 |
| Knight's Place (Windsor) RES. Assoc. Ltd | Households | 1996 |
| Knightsbridge Estates London Ltd | Real estate | 2019 |
| Kolbe Av-Technology Ltd | Professional & scientific | 2011 |
| Kolumbix Ltd | Education | 2012 |
| Komoshun Limited | Information & communication | 2026 |
| Konami Digital Entertainment B.V. | | 2003 |
| Konami Digital Entertainment BV | | 2023 |
| Koppar Group Limited | Financial services | 2023 |
| Kore Platforms Ltd | Information & communication | 2026 |
| Korshia Homes Ltd | Real estate | 2024 |
| Kosha Industries Ltd | Transport & logistics | 2023 |
| Kotcherlakota Resource Ltd | Real estate | 2022 |
| KRD Houses Ltd | Real estate | 2016 |
| Krissas Limited | Wholesale & retail | 2022 |
| Kristina Psychology Services Ltd | Education | 2021 |
| Kroschke UK Ltd | Transport & logistics | 2022 |
| Krystal Klear Exterior Cleaning Ltd | Administrative & support | 2025 |
| KS Boilers Services Ltd | Construction | 2025 |
| KSE Investments Limited | Construction | 2014 |
| Kudur Limited | Professional & scientific | 2025 |
| Kulkarni Surgery Ltd | Health & social care | 2010 |
| Kumtax Limited | Professional & scientific | 2026 |
| Kurkowska Safety Limited | Other services | 2017 |
| Kurlco Limited | Real estate | 2023 |
| Kusmishko Limited | Arts & recreation | 2012 |
| KYU Ltd | Wholesale & retail | 2019 |
| L and S UK Properties Limited | Real estate | 2023 |
| L C Chinn Ltd | Professional & scientific | 2024 |
| L Jones Builders Ltd | Construction | 2019 |
| L&M Business Consulting Industry Limited | Manufacturing | 2021 |
| L'Avenyr Property Company Limited | Real estate | 1996 |
| LA Briosa Limited | Administrative & support | 2021 |
| LA Cantina Catering Limited | Hospitality | 2025 |
| LA Generale Limited | Wholesale & retail | 2011 |
| LA Jolie Maison Limited | Wholesale & retail | 2021 |
| Labarr Consulting Services Ltd | Professional & scientific | 2024 |
| Laborda Estates Limited | Real estate | 2006 |
| Lacuna Partners Limited | Administrative & support | 2020 |
| Lagacybuild Investments Limited | Real estate | 2026 |
| Laguna Consulting Limited | Professional & scientific | 2018 |
| Lakeside Equestrian Centre Limited | Arts & recreation | 2015 |
| Lakeside Stud Ltd | Agriculture & fishing | 2024 |
| Lakeview Accountancy Limited | Professional & scientific | 2009 |
| Lamloet Thai Therapy Ltd | Other services | 2023 |
| Lammas Court,Windsor(Management)Limited | Households | 1971 |
| Lancaster Capital Ventures Ltd | Administrative & support | 1982 |
| Lancaster Contracting Limited | Construction | 1984 |
| Lance Robinson Engineering and Development Limited | Real estate | 2007 |
| Lance Robinson Properties Ltd | Construction | 2014 |
| Lancelot Associates Limited | Professional & scientific | 2024 |
| Lancewood Horticulture Ltd | Administrative & support | 2018 |
| Lanesborough Homes Limited | Construction | 2023 |
| Langdon Customs and Excise Solutions Ltd | Information & communication | 2022 |
| Langlee Business Solutions Ltd | Professional & scientific | 2014 |
| Langley Chiropractic Clinic Limited | Other services | 2010 |
| Langley Hall Arts Limited | Education | 2017 |
| Lanord Capital Limited | Professional & scientific | 2023 |
| Lantern Partners Ltd | Real estate | 2025 |
| Lapis Trading Limited | Wholesale & retail | 2006 |
| Larks Rise (Aston Clinton) Residents Association Limited | Households | 2002 |
| Larodde Ltd | Construction | 2016 |
| Laser Fusion Technologies Ltd | Administrative & support | 2009 |
| Laslett Industries Limited | Wholesale & retail | 2018 |
| Latham Associates Business Consulting Limited | Professional & scientific | 2021 |
| Latham's Accountancy Limited | Professional & scientific | 2025 |
| Lathersmith Ltd | Manufacturing | 2013 |
| Latimer Court (Amersham) Management Company Limited | Households | 2006 |
| Latimer Place Management Company Ltd | Real estate | 2014 |
| Latitude Developments Ltd | Professional & scientific | 2025 |
| Laura Cares Limited | Health & social care | 2017 |
| Laurel Court Management (C.B.) Limited | Real estate | 1994 |
| Lauren Bennett Contracting Limited | Construction | 2022 |
| Lavender Green Flowers Limited | Wholesale & retail | 2005 |
| Lavender Green Gardens Limited | Wholesale & retail | 2015 |
| Lavignac Ltd | Construction | 2017 |
| Lavignac Securities Limited | Professional & scientific | 2012 |
| Lawrence Court (RTE) Limited | Real estate | 2005 |
| Lawrence Court Management Company (Windsor) Limited | Households | 1978 |
| Lawsons Living Ltd | Hospitality | 2022 |
| Lawsons Residential Lettings Ltd | Real estate | 2021 |
| Lawsons Residential Ltd | Real estate | 2021 |
| Layali Night Limited | Hospitality | 2023 |
| Layton Design Limited | Professional & scientific | 2015 |
| LBD Marketing Limited | Information & communication | 2019 |
| LC Sports Performance & Consultancy Ltd | Professional & scientific | 2026 |
| LC25 Marketing Ltd | Professional & scientific | 2025 |