| Jsprosser Ltd | Health & social care | 2018 |
| JST Leisure and Travel Ltd | Manufacturing | 2022 |
| Juali Limited | Financial services | 2026 |
| Jubitus Ltd | Hospitality | 2025 |
| K & K Property Management Ltd | Real estate | 2003 |
| K&J Supplies Ltd | Wholesale & retail | 2026 |
| K&R Aviation Limited | Manufacturing | 2018 |
| KAM Site Services Ltd | Administrative & support | 2026 |
| Kayanel Consulting Ltd | Professional & scientific | 2022 |
| KBG Aviation Engineering Limited | Transport & logistics | 2006 |
| KC Driver Limited | Transport & logistics | 2023 |
| Kdss Services Limited | Transport & logistics | 2007 |
| KE Aero Limited | Manufacturing | 2021 |
| Kenmarg Limited | Hospitality | 2026 |
| Kerslake Properties Limited | Real estate | 2003 |
| Kinder Group Limited | Hospitality | 2006 |
| Kindred Arts CIC | Arts & recreation | 2026 |
| Kiwi Drywall Systems Ltd | Construction | 1999 |
| KKR Catering Ltd | Hospitality | 2021 |
| Knight Aerotech Limited | Transport & logistics | 2012 |
| Kobblers Limited | Wholesale & retail | 2003 |
| Kobblers Treorchy Limited | Other services | 2006 |
| Kovic Aerotech Limited | Manufacturing | 2022 |
| KR Aerotech Limited | Manufacturing | 2015 |
| KR Engineering Limited | Manufacturing | 2006 |
| Kruger Tech Limited | Manufacturing | 2025 |
| KS Engineering EL Limited | Manufacturing | 2024 |
| KWG Engineering & Facilities Maintenance Ltd | Professional & scientific | 2025 |
| Kyle Betteridge Ltd | Transport & logistics | 2023 |
| L JAM Property Limited | Real estate | 2021 |
| L&B Autotech Limited | Wholesale & retail | 2022 |
| Lads & Dads Men's Wellbeing CIC | Health & social care | 2023 |
| Lahmartra Aerotech Limited | Manufacturing | 2015 |
| Lakm Aviation Technical Support Ltd | Manufacturing | 2026 |
| Land, Air and Sea Building and Transport Services Limited | Manufacturing | 2016 |
| Landerson EYE Ltd | Information & communication | 2012 |
| LBN Baby Limited | Wholesale & retail | 2016 |
| LE Homes Ltd | Real estate | 2020 |
| LES Tous Grands Limited | Health & social care | 2006 |
| Letsbespoke Ltd | Manufacturing | 2026 |
| Liberty Estates Limited | Professional & scientific | 2008 |
| Light Blue Electronics Limited | Transport & logistics | 2012 |
| Lighthouse Property Enterprises Limited | Real estate | 2023 |
| Lilly Haha Ltd | Hospitality | 2026 |
| Lindlovu Limited | Administrative & support | 2017 |
| Lismate Limited | Real estate | 1979 |
| Lister Aerotech Limited | Transport & logistics | 2012 |
| Living Well With Lloyd Ashley Ltd | Health & social care | 2020 |
| Llewellyn Engineering Ltd | Professional & scientific | 2021 |
| LLH Design and Build T/A Complete Construction Ltd | Construction | 2022 |
| Lloyd Barnes Consultancy Ltd | Information & communication | 2018 |
| Llys Onnen Management Company Limited | Households | 1991 |
| Lock and Jones Property Limited | Real estate | 2019 |
| Locke Engineering Limited | Manufacturing | 2017 |
| Lord IT UP Limited | Manufacturing | 2019 |
| LQE Ltd | Manufacturing | 2016 |
| LR Morgan Carpentry Limited | Construction | 2016 |
| LTH Aero Ltd | Manufacturing | 2022 |
| Lucky Rabbit Productions Ltd | Information & communication | 2025 |
| Luke Hiscock Engineering Ltd | Manufacturing | 2016 |
| Lumbridge Lettings Ltd | Real estate | 2026 |
| Lumina Design Limited | Construction | 2014 |
| M & F Home Improvements Ltd | Construction | 2002 |
| M & J Leasing Ltd | Administrative & support | 2020 |
| M E Aviation Limited | Manufacturing | 2015 |
| M&L Aviation Limited | Manufacturing | 2018 |
| M-Art-A-Design Limited | Manufacturing | 2017 |
| M-Jet Aircraft Services Limited | Manufacturing | 2022 |
| Mafab Limited | Wholesale & retail | 2024 |
| Maison Move Ltd | Wholesale & retail | 2026 |
| Maison Ombre Ltd | Wholesale & retail | 2026 |
| Maka Mobile Valeting Limited | Administrative & support | 2007 |
| Maltby Innovations Limited | Professional & scientific | 2026 |
| Marine Prop Limited | Real estate | 2023 |
| Mark Rees Engineering Limited | Manufacturing | 2015 |
| Marz Aerotech Limited | Transport & logistics | 2012 |
| Masters Healthy Carers Limited | Health & social care | 2025 |
| Match Developments Limited | Real estate | 2019 |
| Mathern (2008) Limited | Construction | 2008 |
| Matiana Investments Limited | Professional & scientific | 2017 |
| Mattea QA Services Ltd | Professional & scientific | 2025 |
| Matthew WEX Aviation Services Ltd | Manufacturing | 2020 |
| Matthews Aerospace Engineering Limited | Manufacturing | 2024 |
| Maycare Solutions Ltd | Administrative & support | 2024 |
| Mchatton Group Ltd | Financial services | 2023 |
| Mchattons Ltd | Real estate | 2020 |
| Medical & Professional Investment LLP | | 2008 |
| Melah Construction Limited | Construction | 2025 |
| Melah Maintenance Limited | Construction | 2022 |
| Meshgrate Limited | Manufacturing | 2025 |
| Mick Eldridge Limited | Professional & scientific | 2011 |
| Midas Personnel Solutions Limited | Administrative & support | 2012 |
| Mikada Solutions Ltd | Transport & logistics | 2006 |
| Milito Ltd | Real estate | 2023 |
| Minaxi Ltd | Wholesale & retail | 2019 |
| Mindfit Kids Ltd | Health & social care | 2025 |
| Minrela Limited | Construction | 1988 |
| MJW Aerotech Limited | Transport & logistics | 2007 |
| ML Aerotech Limited | Manufacturing | 2016 |
| MLR - Project Management Ltd | Construction | 2017 |