| Infonomix Limited | Professional & scientific | 2008 |
| Innovative Plastering Solutions Limited | Construction | 2016 |
| Integral Assurance Ltd | Professional & scientific | 2024 |
| Integrated Design Studio Ltd | Professional & scientific | 2022 |
| Integrity Seven Limited | Financial services | 2006 |
| Intersolve Limited | Professional & scientific | 1996 |
| Intuitive Systems and Networks Limited | Information & communication | 2008 |
| Iovus Limited | Wholesale & retail | 2017 |
| J & T Tubes Limited | Manufacturing | 1999 |
| J & V Kotze Ltd | Health & social care | 2011 |
| J Christie Consulting Ltd | Administrative & support | 2022 |
| J Grace Private Ltd | Health & social care | 2017 |
| J Hooper Construction Limited | Construction | 2003 |
| J.J Electrical Contractor (Dorset) Ltd | Construction | 2026 |
| J.V Marston Builders Limited | Construction | 2013 |
| Jain & Jain Limited | Health & social care | 2011 |
| Janice Dempsey Consulting Limited | Information & communication | 2026 |
| JBX Enterprises Ltd | Wholesale & retail | 2023 |
| JC Property Ltd | Real estate | 2015 |
| JDW Plumbing Ltd | Construction | 2018 |
| Jefferson Avenue Airbnb Ltd | Real estate | 2020 |
| Jgab Ltd | Health & social care | 2021 |
| Jigsaw Physiotherapy Limited | Health & social care | 2015 |
| JMB Management Ltd | Real estate | 2021 |
| JMJ Foods Ltd | Wholesale & retail | 2022 |
| JMJ Seafoods Ltd | Wholesale & retail | 2025 |
| Jonathan Lippiatt Ltd | Health & social care | 2022 |
| JP Management & Carpentry Limited | Construction | 2019 |
| Jpnm Holdings Ltd | Financial services | 2025 |
| JRV Consultancy Limited | Real estate | 2014 |
| JS Education Ltd | Professional & scientific | 2020 |
| JSC Paving & Landscaping Ltd | Construction | 2015 |
| Jubilee Builders Ltd | Construction | 2021 |
| Just 4 U Day Club Limited | Health & social care | 2013 |
| JXP Properties Ltd | Real estate | 2025 |
| K B Pools & Spas Limited | Construction | 2005 |
| K.M. Financial Consultants (Wessex) Limited | Financial services | 2001 |
| KAN Property Management Limited | Real estate | 2010 |
| KB Pools and Hottubs Ltd | Extraterritorial | 2024 |
| Keratin Kits Ltd | Wholesale & retail | 2011 |
| Kerry Jayne Designs Ltd | Professional & scientific | 2020 |
| Kestrel Medical Limited | Wholesale & retail | 2000 |
| KHE Osteopathy Ltd | Health & social care | 2021 |
| Kitching Consulting Ltd | Professional & scientific | 2017 |
| Kiwi Prints Limited | Manufacturing | 2023 |
| KLM Property Management Limited | Households | 2012 |
| Kontado Limited | Professional & scientific | 2013 |
| Krbp Limited | Real estate | 2020 |
| Kult Collective Ltd | Professional & scientific | 2024 |
| L. J. Gardner Transport Limited | Transport & logistics | 2011 |
| Lale Ltd | Hospitality | 2025 |
| Land Sea Air Solutions Ltd | Professional & scientific | 2016 |
| Landscape and Drainage Solutions Ltd | Professional & scientific | 2018 |
| Lawrence School of Motoring Ltd | Education | 2019 |
| Layton Court Management Company Limited | Households | 1988 |
| Leonard Radiology Limited | Health & social care | 2019 |
| Less Risk IT Ltd | Information & communication | 2005 |
| LET Logistics Ltd | Transport & logistics | 2026 |
| LET Maintenance Ltd | Construction | 2022 |
| Level & Square Construction Limited | Construction | 2007 |
| LG Howson Ltd | Construction | 2022 |
| Lhqa Limited | Information & communication | 2023 |
| Likelihood Creative Ltd | Information & communication | 2022 |
| Lilie Fish Ltd | Wholesale & retail | 2023 |
| Limitless Craeft Ltd | Manufacturing | 2025 |
| Lionel Gregory Limited | Professional & scientific | 1986 |
| LKB Apparel Consulting Ltd | Professional & scientific | 2012 |
| LM Carpentry & Building Ltd | Construction | 2026 |
| Local Digital Media Ltd | Information & communication | 2025 |
| London Residential Surveys Limited | Other services | 2021 |
| London ZTS Marine Design & Consultant Co., Ltd | Professional & scientific | 2007 |
| Louell Investments Limited | Real estate | 2018 |
| Louev Property Ltd | Construction | 2025 |
| Love Projects Home Improvements Ltd | Construction | 2020 |
| Lovehearth Ltd | Information & communication | 2026 |
| Lulu's Playhouse Ltd | Administrative & support | 2024 |
| Luxaco Elite Limited | Wholesale & retail | 2024 |
| Luxdent Limited | Health & social care | 2010 |
| M & G Slocock Ltd | Financial services | 2013 |
| M B H Electrical Ltd | Professional & scientific | 2023 |
| M D Photography Limited | Professional & scientific | 2012 |
| M J Burt Property Maintenance Limited | Construction | 2004 |
| Machine Sales and Services (Poole) Limited | Wholesale & retail | 1983 |
| Macintosh & Mizen Limited | Wholesale & retail | 1957 |
| MAD Hatters Emporium Ltd | Administrative & support | 2020 |
| Mando Consulting Ltd | Financial services | 2021 |
| Maple (261) Limited | Households | 2005 |
| Maria Amey Salon and Academy Ltd | Other services | 2025 |
| Mariyam Limited | Wholesale & retail | 2025 |
| Marlin Park Management Company Limited | Real estate | 2005 |
| Marriott-Brown Investments Ltd | Real estate | 2020 |
| Martin & Co Carpenters Ltd | Manufacturing | 2015 |
| Martin Realty Ltd | Real estate | 2024 |
| Mason & Family Investments Ltd | Real estate | 1966 |
| Matrics Consult Ltd | Professional & scientific | 2001 |
| Mattchimattchi Ltd | Wholesale & retail | 2023 |
| Matthew Hills Limited | Administrative & support | 2008 |
| MAV Carpentry & Construction Ltd | Construction | 2022 |
| MB Kraken Holdings Ltd | Administrative & support | 2024 |
| Mbsr Holdings Ltd | Real estate | 2024 |