| Juduby Property Ltd | Financial services | 2024 |
| Julie Condliffe Academy Limited | Financial services | 2018 |
| Justs Home Construction Limited | Construction | 2021 |
| JVS Group Ltd | Wholesale & retail | 2022 |
| JVS MOT Ltd | Wholesale & retail | 2020 |
| JWF Carpentry Ltd | Manufacturing | 2024 |
| JZ Commercials Ltd | Wholesale & retail | 2025 |
| K&D Services Ltd | Construction | 2026 |
| K2 Comms Ltd | Construction | 2023 |
| Kala Associates Ltd | Arts & recreation | 2022 |
| Kalibre Automatic Doors Ltd | Construction | 2020 |
| Kandu Interiors Limited | Wholesale & retail | 2012 |
| Kandu Limited | Professional & scientific | 2014 |
| Kasi Traders Ltd | Wholesale & retail | 2020 |
| Katie's Cleaning and Maintenance Service Ltd | Administrative & support | 2019 |
| Kausi Investments Ltd | Real estate | 2025 |
| KB Photography Ltd | Professional & scientific | 2023 |
| KBB Recruitment Ltd | Administrative & support | 2020 |
| KBO Chojecki Waldemar Ltd | Wholesale & retail | 2016 |
| KC Consult Ltd | Administrative & support | 2025 |
| KCR Property Maintenance Ltd | Construction | 2025 |
| KD Direct Inc Ltd | Hospitality | 2015 |
| KDC Renovations Limited | Construction | 2022 |
| Keemah Limited | Information & communication | 2008 |
| Kellico Exteriors Limited | Construction | 2021 |
| Kelly Lighting Solutions Limited | Manufacturing | 2020 |
| Kempston Controls (Manufacturing) Ltd | Manufacturing | 2021 |
| Kempston Group (UK) Limited | Financial services | 2024 |
| Kempston Group Holdings Limited | Financial services | 2024 |
| Kenswa Investments Limited | Real estate | 2020 |
| Kestrel Footwear Limited | Wholesale & retail | 2014 |
| Keysoe Developments Ltd | Construction | 2023 |
| Keytree Ltd | Manufacturing | 2021 |
| KGM2016 Ltd | Transport & logistics | 2023 |
| Kharidel Care Connect Ltd | Administrative & support | 2026 |
| Kidman & Schulze Limited | Real estate | 2023 |
| Kidshome Technologies Ltd | Information & communication | 2025 |
| Kierans Aquatic Shack Limited | Agriculture & fishing | 2022 |
| Killickzinc Limited | Construction | 2018 |
| Kimbell Consulting Limited | Professional & scientific | 2015 |
| Kincyro Limited | Health & social care | 2025 |
| KIP Mcgrath Rushden LP | | 2024 |
| Kirsty Burton Ltd | Other services | 2024 |
| Kishan Music Ltd | Information & communication | 2024 |
| Kishans Fish Bar Limited | Hospitality | 2016 |
| Kitchens Contracts Ltd | Construction | 2008 |
| KL Services Ltd | Information & communication | 2021 |
| KMA Williams Consulting Ltd | Professional & scientific | 2026 |
| Knights of the Oak Limited | Wholesale & retail | 2025 |
| Kodai Labs Limited | Information & communication | 2026 |
| Kojus Motors Ltd | Wholesale & retail | 2025 |
| KRD Property Ltd | Real estate | 2022 |
| Krollen Property Ltd | Real estate | 2025 |
| KTB Business Services Ltd | Administrative & support | 2018 |
| KTD Plumbing & Heating Ltd | Construction | 2026 |
| KV and Engineering Limited | Professional & scientific | 2026 |
| KY Janus Limited | Real estate | 2025 |
| L & J Luxury Soft Play Ltd | Arts & recreation | 2023 |
| L a Business Ltd | Professional & scientific | 2020 |
| L Constantin Ltd | Construction | 2020 |
| L Sambor Ltd | Construction | 2015 |
| L W L H D Ltd | Other services | 2023 |
| L.M Fitness and Consultant Limited | Construction | 2020 |
| L4 Civil Engineering Limited | Construction | 2016 |
| L4 Holdings Limited | Financial services | 2026 |
| L4 Plant Limited | Administrative & support | 2026 |
| LA Building & Renovations Limited | Construction | 2019 |
| LA Estrella Restaurant Ltd | Hospitality | 2018 |
| LA Famiglia Ltd | Hospitality | 2025 |
| LAB Estates Ltd | Real estate | 2022 |
| LAB Property Solutions Ltd | Real estate | 2020 |
| Ladwa (Engineering) Limited | Professional & scientific | 1973 |
| Lamb & Watt Vintners Limited | Extraterritorial | 1993 |
| Lancaster Homes and Development Ltd | Construction | 2019 |
| Land Prune Ltd | Agriculture & fishing | 2017 |
| LAS Medical Writing Limited | Professional & scientific | 2017 |
| Lashphoria Ltd | Wholesale & retail | 2025 |
| Launch & Loop Limited | Professional & scientific | 2025 |
| Lazer Hawk Ltd | Information & communication | 2023 |
| Lc's Sales Ltd | Wholesale & retail | 2018 |
| Leadersmithing LLP | | 2011 |
| Leading Edge Simulation Ltd | Professional & scientific | 2023 |
| League of Extraordinary Investors Limited | Professional & scientific | 2018 |
| Leaseholders 50 Brightwell Avenue RTM Company Limited | Households | 2013 |
| Leftway Group Limited | Manufacturing | 2015 |
| Legal Pathways Advisory Ltd | Professional & scientific | 2026 |
| Legal Pathways Project CIC | Public administration | 2025 |
| Legatum Wealth Management Limited | Professional & scientific | 2019 |
| Legionella Risk Solutions Ltd | Water & waste | 2016 |
| Lemon POP Limited | Arts & recreation | 2015 |
| Lemonpop Workshops CIC | Education | 2023 |
| Lesterfield Services Ltd | Administrative & support | 2025 |
| Leszczynski Repairs Ltd | Wholesale & retail | 2021 |
| Lets for Pets Limited | Real estate | 2023 |
| Leverage AI Ltd | Information & communication | 2023 |
| LG Venezian Artizan Ltd | Construction | 2021 |
| LGH Transport Ltd | Transport & logistics | 2024 |
| Liberty Property Limited | Real estate | 2018 |
| Libra Tax Ltd | Manufacturing | 2018 |
| Lilyring Ltd | Transport & logistics | 2014 |