| Koks Real Estate Limited | Real estate | 2026 |
| Koumi Family Partnership LLP | | 2019 |
| KPB Associates Ltd | Professional & scientific | 2025 |
| Kranwerke UK Limited | Other services | 2024 |
| Kruk Prop LLP | | 2017 |
| Krukee Ltd | Real estate | 2016 |
| KT Electrical Limited | Professional & scientific | 2014 |
| Kunal & Sanbir Mehra Family Partnership LLP | | 2020 |
| Kurups Limited | Health & social care | 2010 |
| Kutting Korner Limited | Other services | 2018 |
| L Allen WP Ltd | Professional & scientific | 2024 |
| L Duffey & I EDE WP Ltd | Administrative & support | 2024 |
| L Kidd WP Ltd | Professional & scientific | 2024 |
| L R Coatings Ltd | Construction | 2023 |
| L Stevenson WP Ltd | Administrative & support | 2024 |
| L&B Consulting Group Ltd | Professional & scientific | 2025 |
| L&C Property Developments Ltd | Real estate | 2022 |
| L&Co Hair Limited | Other services | 2023 |
| L&M Cabling Solutions Ltd | Information & communication | 2025 |
| L,M & C Properties Limited | Real estate | 2023 |
| L.Davis Project Management Ltd | Professional & scientific | 2023 |
| LA Buona Pizza UK Ltd | Hospitality | 2022 |
| LA Porto Italiano Limited | Hospitality | 2014 |
| Lakeview Company NE Limited | Construction | 2018 |
| Lakh Creative Investments Limited | Information & communication | 2021 |
| LAM Welding Engineering Services Ltd | Professional & scientific | 2020 |
| Lancashire Media & Production Studios Ltd | Information & communication | 2025 |
| Landport Labs Limited | Information & communication | 2025 |
| Landscape Networks Ltd | Information & communication | 2014 |
| Landzar Partnership LLP | | 2023 |
| Langley Holdings Partnership LLP | | 2021 |
| Lara Bella Limited | Other services | 2018 |
| Lasr Studio Ltd | Other services | 2026 |
| Latto Family Holdings Ltd | Real estate | 2023 |
| Latto Family Partnership LLP | | 2023 |
| Laura B Catering Limited | Wholesale & retail | 2012 |
| Lawson Family Partnership LLP | | 2021 |
| Lawton Land and Developments Ltd | Professional & scientific | 2025 |
| Laycock Ltd | Professional & scientific | 2010 |
| Laycock Technical Services Limited | Administrative & support | 2012 |
| LB Optics Ltd | Health & social care | 2025 |
| LDC OIL & GAS Instrumentation Ltd | Professional & scientific | 2011 |
| LDS Express Ltd T/A Move IT Automotive Ltd | Transport & logistics | 2018 |
| Lead Pharma Healthcare Limited | Wholesale & retail | 2023 |
| LEC5 Rail Limited | Professional & scientific | 2014 |
| LEC5 Rail Personnel Limited | Administrative & support | 2012 |
| Ledger Signals Limited | Information & communication | 2025 |
| Leeds Cataract and Cornea Care Ltd | Health & social care | 2025 |
| Leigh & Sonia Jones Family P'Ship LLP | | 2021 |
| Leishman IT Solutions Ltd | Information & communication | 2020 |
| Lemontop Limited | Wholesale & retail | 2012 |
| Lennox Construction NE Ltd | Construction | 2024 |
| LET Belle VUE Consulting Limited | Professional & scientific | 2024 |
| LET Belle VUE Design & Construction Limited | Construction | 2022 |
| LET Belle VUE Estates Limited | Real estate | 2018 |
| LET Belle VUE Limited | Construction | 2016 |
| LET US Letts Ltd | Real estate | 2020 |
| Lewczynski Family Holdings Ltd | Real estate | 2017 |
| Lewczynski Family Partnership LLP | | 2017 |
| Lewis Scada Services Limited | Professional & scientific | 2023 |
| Lewis Surveyors Energy Ltd | Professional & scientific | 2013 |
| LI Food Limited | Hospitality | 2025 |
| Libertad Holdings Ltd | Financial services | 2021 |
| Liberty Stays Ltd | Real estate | 2022 |
| Life Coach - Perspectives Limited | Health & social care | 2021 |
| Lighthouse Locum Services Ltd | Wholesale & retail | 2024 |
| LIM TAN Property Ltd | Real estate | 2023 |
| Limilo Ltd. | Information & communication | 2011 |
| Limitless Sports and Learning Centre CIC | Education | 2025 |
| Lindberg Family Partnership LLP | | 2021 |
| Lindsay & Jones Properties Ltd | Real estate | 2023 |
| Lingfield Point (Baldwin Lane) Management Company Limited | Real estate | 2018 |
| Links Golf Clothing Ltd | Manufacturing | 2025 |
| Lins Family Partnership LLP | | 2023 |
| Lins Property Developments Limited | Real estate | 2003 |
| Lisa Jayne Simpson Limited | Professional & scientific | 2017 |
| List Lettings Ltd | Real estate | 2024 |
| Lizard Lettings Ltd | Real estate | 2023 |
| LJ Majors Logistics Ltd | Transport & logistics | 2025 |
| LKE Family Limited | Financial services | 2022 |
| Ll&K Consultants Ltd | Construction | 2024 |
| LLR NDT Ltd | Professional & scientific | 2026 |
| LM Properties (NE) Limited | Real estate | 2020 |
| LMM80 Design Limited | Administrative & support | 2007 |
| LND Associates Ltd | Administrative & support | 2018 |
| LNG & SK Ltd | Real estate | 2026 |
| Lobban Family Holdings Ltd | Real estate | 2017 |
| Lobster POT (Bognor Regis) Ltd | Hospitality | 2007 |
| Lodge and TUB Holidays Limited | Hospitality | 2017 |
| Logis 1 Limited | Real estate | 2017 |
| Londinium Luxury Ltd | Wholesale & retail | 2026 |
| Loose Grip Studio Limited | Professional & scientific | 2024 |
| Lopez Properties Limited | Real estate | 2025 |
| Lotus Leaf Properties Partnership LLP | | 2020 |
| Lovely Lawns 36 Ltd | Administrative & support | 2023 |
| LP400 Ltd | Real estate | 2021 |
| LPD Lettings Ltd | Real estate | 2018 |
| LRC Instruments Limited | Professional & scientific | 2013 |
| LTA Consultants Limited | Professional & scientific | 2018 |
| Ltd Estates Limited | Real estate | 2025 |