| Kumrat Construction Limited | Construction | 2026 |
| Kupid's Disco Ltd | Wholesale & retail | 2025 |
| Kurdish Cutz Ltd | Other services | 2025 |
| Kurrajong Limited | Professional & scientific | 2015 |
| Kurt Marine Services Ltd | Manufacturing | 2017 |
| Kustom Coatings Ltd | Manufacturing | 2018 |
| Kuuma Ltd | Manufacturing | 1999 |
| Kvist Architecture and Design Ltd | Professional & scientific | 2016 |
| Kvls Mental Health Support Ltd | Health & social care | 2022 |
| KW Customs Ltd | Manufacturing | 2023 |
| Kwackers Event Food Ltd | Hospitality | 2023 |
| Kwackers Festival Food Ltd | Hospitality | 2023 |
| Kwanza Property & Design Ltd | Real estate | 2024 |
| Kwbusiness Ltd | Households | 2025 |
| Kwesdel Ltd | Transport & logistics | 2026 |
| Kwiatek Deli Ltd | Wholesale & retail | 2018 |
| Kwik Change Limited | Wholesale & retail | 2025 |
| Kwikmrt UK Ltd | Information & communication | 2020 |
| Kwmd Marketing Ltd | Professional & scientific | 2025 |
| KWR Services Ltd | Wholesale & retail | 2018 |
| Kymrod Limited | Information & communication | 2024 |
| Kynd Medical and Wellness Limited | Other services | 2022 |
| Kynsale Limited | Professional & scientific | 2003 |
| Kyoshi Ltd | Transport & logistics | 2026 |
| Kyoto Rooms Limited | Hospitality | 2023 |
| Kysoh Limited | Professional & scientific | 2015 |
| L & a Flooring Ltd | Construction | 2021 |
| L & C Land Developments Ltd | Real estate | 2026 |
| L & R Easyliving Limited | Real estate | 2016 |
| L a Business Consultants Ltd | Administrative & support | 2014 |
| L a Cabling Limited | Construction | 2014 |
| L a J UK Properties Limited | Real estate | 2018 |
| L a Plumbing and Heating Limited | Construction | 2025 |
| L and E Fitting Limited | Construction | 2017 |
| L B Lambert Ltd | Construction | 2018 |
| L Baker GAS Solutions Limited | Construction | 2018 |
| L Byrne Brickwork and Building Ltd | Construction | 2025 |
| L C H Motor Company Limited | Wholesale & retail | 2001 |
| L C Property Solutions Ltd | Real estate | 2026 |
| L C Yachting Limited | Manufacturing | 2019 |
| L D L Plumbing & Heating Ltd | Construction | 2021 |
| L G Whitfield Ltd | Construction | 2022 |
| L M Contractors Southern Ltd | Construction | 2017 |
| L M Electrical Contractors Limited | Manufacturing | 2014 |
| L S Property Developments Ltd | Real estate | 2010 |
| L S Stones Ltd | Manufacturing | 2025 |
| L Smith Brickwork and Construction Ltd | Construction | 2023 |
| L&A Mechanics Ltd | Wholesale & retail | 2022 |
| L&G Property Ltd | Construction | 2011 |
| L&K Mortgage Solutions Limited | Financial services | 2023 |
| L&L Construction Limited | Construction | 2024 |
| L&S Flooring Limited | Construction | 2023 |
| L&Z Coffee Ltd | Hospitality | 2020 |
| L'Eternite Limited | Extraterritorial | 2013 |
| L'Incontro Room Ltd | Hospitality | 2025 |
| L-D Applications Limited | Information & communication | 2005 |
| L. and L.Trustees Limited | Construction | 1954 |
| L.A Coatings Ltd | Construction | 2025 |
| L.E Boxing Ltd | Arts & recreation | 2019 |
| L.M.D. Designs Limited | Professional & scientific | 2018 |
| L.P.D Brickwork Limited | Construction | 2017 |
| L11NK Limited | Information & communication | 2021 |
| LA Collina Ltd | Hospitality | 2025 |
| LA Cucu Ltd | Wholesale & retail | 2026 |
| LA Digital Print & Mailing Ltd | Manufacturing | 2009 |
| LA Divine Limited | Wholesale & retail | 2026 |
| LA Dolce Vita Southern Ltd | Other services | 2019 |
| LA Hally Architect Limited | Professional & scientific | 2015 |
| LA IVA Services Limited | Wholesale & retail | 2019 |
| LA Luna Estates Ltd | Hospitality | 2022 |
| LA Magdalena Ltd | Wholesale & retail | 2023 |
| LA Nails 339 Ltd | Other services | 2024 |
| LA Perla (UK) Ltd | Wholesale & retail | 1998 |
| LA Perla Global Management (UK) Limited | Manufacturing | 2010 |
| LA Pharm Ltd | Wholesale & retail | 2022 |
| LA Razdu Ltd | Hospitality | 2025 |
| LA Solent Retail Ltd | Wholesale & retail | 2026 |
| LA Tasca Restaurants Limited | Hospitality | 1993 |
| LA Toxica Ltd | Wholesale & retail | 2024 |
| Laadol Engineering Ltd | Professional & scientific | 2018 |
| LAB378 Limited | Information & communication | 2025 |
| LAB402 Consulting and Development Ltd | Information & communication | 2024 |
| Laborious Ltd | Professional & scientific | 2025 |
| Laborious.Ai Ltd | Professional & scientific | 2025 |
| Laburnum Court Management Company Limited | Households | 1993 |
| Labvolution Limited | Professional & scientific | 2014 |
| Lacertas Holdings Ltd | Wholesale & retail | 2019 |
| Lacey's Quality Decorating Limited | Construction | 2016 |
| Lacey’S Shooting Services Ltd | Wholesale & retail | 2026 |
| Ladis Autos Ltd | Wholesale & retail | 2023 |
| Ladybirds Pre-School Southampton | Education | 2010 |
| LAF Transport Ltd | Transport & logistics | 2025 |
| Lafuente Experiences Limited | Arts & recreation | 2025 |
| Lafuente Ipco Limited | Professional & scientific | 2025 |
| Lagarcia Ltd | Wholesale & retail | 2024 |
| Lainston Asset Management Ltd | Real estate | 2016 |
| Lainston Broadway LLP | | 2015 |
| Lainston Commercial Limited | Construction | 2016 |
| Lainston Commercial Two Limited | Real estate | 2020 |
| Lainston Developments Ltd | Construction | 2005 |