| K Hall Consultancy Ltd | Construction | 2018 |
| K L R Industrial Ltd | Construction | 2008 |
| K'S Cuisine Bruerne Ltd | Hospitality | 2025 |
| K.W. Richardson Limited | Construction | 2004 |
| K2 Construction Ltd | Construction | 2006 |
| Karlikowska Investments Limited | Financial services | 2023 |
| Karma Mark Start Ltd | Information & communication | 2025 |
| Kaynescustoms Ltd | Wholesale & retail | 2026 |
| KC Property Surveys Ltd | Professional & scientific | 2020 |
| KD Scaffold Contractors Ltd | Construction | 2019 |
| Kearley & Tonge Limited | Extraterritorial | 2001 |
| Kent Street Consultants Limited | Professional & scientific | 2019 |
| Kent Surveying Limited | Construction | 2021 |
| Kerridge Cullen Property Ltd | Real estate | 2018 |
| Kerridges Marlow LLP | | 2012 |
| Keystone Insight Ltd | Professional & scientific | 2025 |
| Keystone Lettings Limited | Real estate | 2017 |
| KG Digital Ltd | Information & communication | 2019 |
| KH London Limited | Professional & scientific | 2015 |
| Kidbrook Godalming Management Company Ltd | Households | 2026 |
| Kidbrook Kingston Management Company Ltd | Households | 2026 |
| Kilrush Consultancy Limited | Professional & scientific | 1997 |
| Kinecroft Properties Ltd | Construction | 2024 |
| Kinesis AI Ltd | Information & communication | 2025 |
| King KAY & Co Ltd | Hospitality | 2014 |
| Kinghams Hairdressers Ltd | Other services | 2024 |
| Kingsfield Place Management Company Limited | Households | 1998 |
| Kirkpatrick Bespoke Limited | Construction | 2014 |
| Kiyomasa Limited | Real estate | 2020 |
| Kode Fitness Limited | Arts & recreation | 2024 |
| Kola Holdings Ltd | Financial services | 2019 |
| Kona Asset 5 Limited | Energy | 2024 |
| Kona Asset 6 Limited | Energy | 2024 |
| Kona Asset 7 Limited | Energy | 2024 |
| Kona Asset 8 Limited | Energy | 2024 |
| Koutsou Consulting Limited | Professional & scientific | 2016 |
| KP Civil Engineering Limited | Construction | 2014 |
| Kpsmc Ltd | Construction | 2024 |
| KRW Outsourcing LLP | | 2011 |
| KRW Tax Planning Limited | Professional & scientific | 2023 |
| KSC Global Consultants Limited | Professional & scientific | 2014 |
| KTM Sportmotorcycle UK Limited | Wholesale & retail | 1998 |
| Kubah Properties Limited | Real estate | 2026 |
| Kupora Pharmaceuticals Group Ltd | Financial services | 2026 |
| KW Special Projects Limited | Professional & scientific | 2012 |
| KYG Property Ltd | Real estate | 2025 |
| L E Strategic Solutions Ltd | Professional & scientific | 2025 |
| L J Brown UK Limited | Construction | 2023 |
| LA Team Collective Ltd | Information & communication | 2018 |
| Laan Associates Limited | Administrative & support | 2003 |
| LAB Thread Ltd | Information & communication | 2024 |
| Labrum Engineering Limited | Construction | 2020 |
| Lactodorum Limited | Real estate | 2021 |
| Lactodorum Whiskey Club LP | | 2021 |
| Lamb Aldwick Ltd | Real estate | 2025 |
| Lamb Hawthorn Ltd | Real estate | 2025 |
| Lamb Property Holdings Ltd | Financial services | 2020 |
| Lamb Property Investments Limited | Real estate | 2018 |
| Lamb Property Leasehold Limited | Real estate | 2020 |
| Lamb Property Services Ltd | Real estate | 2017 |
| Landmark Contractors Limited | Construction | 2018 |
| Landmark Divitiae UK Ltd | Real estate | 2017 |
| Landmark Equestrian Contractors LLP | | 2007 |
| Langford Estates Limited | Real estate | 2025 |
| Langton & Worth Holdings Ltd | Other services | 2022 |
| Larrilux Ltd | Wholesale & retail | 2025 |
| Laura MCN Limited | Wholesale & retail | 2016 |
| Laurel House Investments Ltd | Real estate | 2026 |
| Laurel Property Ltd | Construction | 2006 |
| Lawrence Ecommerce Limited | Wholesale & retail | 2024 |
| Lawrence Property Management Limited | Real estate | 2016 |
| Lazuli Property Ltd | Construction | 2019 |
| Lazy Bear PUB Co Ltd | Hospitality | 2018 |
| Lbhgeo Ltd. | Professional & scientific | 2003 |
| LE Bois Ltd | Manufacturing | 2023 |
| LE Grand Fromage (LGF) Engineering Ltd | Professional & scientific | 2025 |
| Leader Projects Ltd | Professional & scientific | 2015 |
| Lean Construction Holdings Limited | Professional & scientific | 2018 |
| Lean Construction International Limited | Extraterritorial | 2021 |
| Lenbo Limited | Financial services | 2022 |
| LEO and Josh Golf Organisation Ltd | Arts & recreation | 2023 |
| LEO Associates Limited | Professional & scientific | 1988 |
| LEO Bodnar (Electronics) Ltd | Manufacturing | 2014 |
| LEO Property 1887 Ltd | Real estate | 2021 |
| Letco MK Ltd | Real estate | 2018 |
| LFP Consulting Limited | Professional & scientific | 2020 |
| LG IP Limited | Administrative & support | 2025 |
| LIBRA7 Fleet Services Limited | Wholesale & retail | 2017 |
| Lily Systems Limited | Information & communication | 2006 |
| Lilynoknots Limited | Wholesale & retail | 2025 |
| Limitless Equity Ltd | Financial services | 2025 |
| Lincs Waste Management Solutions Ltd | Wholesale & retail | 2019 |
| Lingobridge Limited | Manufacturing | 2023 |
| Linnell Brothers Holdings Limited | Financial services | 2021 |
| Linnell Brothers Limited | Manufacturing | 1940 |
| Lion Court Northampton UK Ltd | Real estate | 2021 |
| Listers Geotechnical Consultants Limited | Professional & scientific | 2007 |
| Litchborough Property Limited | Real estate | 2020 |
| Little Laughs Ltd | Wholesale & retail | 2025 |
| Little Spark Learning Ltd | Education | 2025 |