| JAY F M Services Ltd. | Construction | 2015 |
| JBA Calibration Services Ltd | Manufacturing | 2019 |
| Jennifer Aitken Translations Ltd | Professional & scientific | 2025 |
| Jilam Properties Limited | Real estate | 2018 |
| JMI Process Consultants Ltd | Administrative & support | 2026 |
| JOG Labs Ltd | Information & communication | 2026 |
| Johmar Medical Services Limited | Real estate | 2012 |
| John a Walker Limited | Manufacturing | 2023 |
| Jonesincorp Ltd | Health & social care | 2018 |
| JP Thomson Design Engineering Limited | Professional & scientific | 2020 |
| Juknevicius Ltd | Health & social care | 2023 |
| Just BE Productions Ltd | Information & communication | 2026 |
| Just Drone IT Ltd | Other services | 2023 |
| JWH Innovation Ltd | Information & communication | 2025 |
| K.R. Rollinson Consultants Limited | Agriculture & fishing | 1979 |
| Kaleden Limited | Professional & scientific | 2016 |
| Kbpharm Limited | Health & social care | 2010 |
| KBR Property Services Ltd | Real estate | 2021 |
| Kcltd Limited | Other services | 2021 |
| Kelemen Plastic Surgery Ltd | Health & social care | 2022 |
| Kids Club 2021 Limited | Education | 2021 |
| King Nexus Ltd | Financial services | 2025 |
| Kingston Dent Specialist Limited | Wholesale & retail | 2019 |
| Kingston Medisolutions Ltd | Health & social care | 2013 |
| Kingston Modular Systems Limited | Construction | 2016 |
| Kingstown Saddlery Ltd | Transport & logistics | 2007 |
| Kirklea Auto Brokers Limited | Wholesale & retail | 2014 |
| KMB Law Ltd | Professional & scientific | 2021 |
| KNM Psychiatry Limited | Health & social care | 2024 |
| Koodal Limited | Wholesale & retail | 2020 |
| Kordhaku Investment Ltd | Real estate | 2025 |
| Krishnan Medical Services Ltd | Real estate | 2016 |
| KSL Academy Ltd | Other services | 2026 |
| L & S Hair Events Limited | Other services | 2022 |
| L4I Ltd | Professional & scientific | 2019 |
| Label Metrics Limited | Manufacturing | 2011 |
| Laelaps Ltd | Administrative & support | 2017 |
| Laetare Cardiology Ltd. | Health & social care | 2019 |
| Lakeland Orthotics Ltd | Manufacturing | 2015 |
| Lancaster Bennett Limited | Construction | 2009 |
| Layton Enterprises Ltd | Professional & scientific | 2010 |
| Leadercoach Ltd | Professional & scientific | 2010 |
| LEC Tech Solutions Ltd | Construction | 2020 |
| Leckhampton Computers Limited | Information & communication | 1980 |
| LEE Williamson Consulting Limited | Professional & scientific | 2013 |
| Leeb Property Ltd | Real estate | 2025 |
| Lets Go Bucket Listing Ltd. | Administrative & support | 2015 |
| Lewisml Ltd | Administrative & support | 2025 |
| Lime Sure Limited | Other services | 2025 |
| Liquid Plumbing Solutions (Brough) Limited | Construction | 2011 |
| Loncaster Limited | Construction | 1991 |
| London Cartridge Company Limited | Arts & recreation | 1997 |
| Longacre Holdings Limited | Real estate | 1942 |
| LOT 16 Limited | Professional & scientific | 2013 |
| Lovely Lilly’S Ltd | Agriculture & fishing | 2022 |
| LOW Street Properties Limited | Real estate | 2012 |
| Lowsons Property Ltd | Real estate | 2024 |
| Lunchbox Theatrical Productions Limited | Arts & recreation | 2004 |
| Lupa Lets Limited | Real estate | 2023 |
| Lupa Properties Limited | Real estate | 2023 |
| Lutkin-Taylor Developments Limited | Real estate | 2013 |
| Lya's Deals Ltd | Wholesale & retail | 2019 |
| M J Hope Builders Limited | Construction | 2011 |
| M L Simpson Ltd | Construction | 2014 |
| M&G Medical Limited | Health & social care | 2024 |
| M&T Investments Limited | Real estate | 2018 |
| M2 Property Development Limited | Real estate | 2012 |
| Maavika Ltd | Hospitality | 2025 |
| Mainserv Ltd | Construction | 2019 |
| Malfi (Yorkshire) Limited | Financial services | 2020 |
| Mali Kruz Lettings Ltd | Real estate | 2026 |
| Mammoth Facilities Management Limited | Construction | 2020 |
| Manor Humber Limited | Hospitality | 2018 |
| Manor Mill Resort Limited | Construction | 2016 |
| Manor Property Holdings Ltd | Administrative & support | 2011 |
| Manz Limited | Health & social care | 2025 |
| Mark on Point Ltd | Wholesale & retail | 2025 |
| Markech Properties Limited | Real estate | 2016 |
| Master Marketing Products Limited | Wholesale & retail | 1983 |
| Mayfair Software Limited | Information & communication | 1999 |
| Maysons Developments Ltd | Construction | 2018 |
| MBB Technologies Ltd | Wholesale & retail | 2021 |
| Meadley International (Transport) Limited | Wholesale & retail | 1982 |
| Meadowmay Limited | Construction | 2007 |
| Medic for YOU Limited | Health & social care | 2016 |
| Melrose Market Limited | Wholesale & retail | 2015 |
| Mensuro Limited | Information & communication | 2026 |
| Metheni Limited | Construction | 2016 |
| Mettle PUB Co (BC) Ltd | Hospitality | 2026 |
| Mettle PUB Co (HC) Ltd | Hospitality | 2025 |
| Mettle PUB Co (HM) Ltd | Hospitality | 2025 |
| Mettle PUB Co (HS) Ltd | Hospitality | 2026 |
| Mettle PUB Co (TI) Ltd | Hospitality | 2026 |
| Mettle PUB Co Holdings Ltd | Hospitality | 2026 |
| Mettle PUB Co Ltd | Hospitality | 2025 |
| MH 24 Assets Limited | Real estate | 2025 |
| MH 24 Limited | Health & social care | 2023 |
| MHL Cassanell Construction and Maintenance Limited | Construction | 2023 |
| MHL Cassanell Property Co. Ltd | Real estate | 2023 |
| Mick Jordan Construction Services Limited | Construction | 2002 |