| Ivy’S Cleaning Services Ltd | Administrative & support | 2023 |
| Iwco Ltd | Wholesale & retail | 2023 |
| J & E Electrical Services Ltd | Construction | 2019 |
| J & N Marketing Limited | Other services | 2022 |
| J Bishop Holdings Ltd | Financial services | 2026 |
| J Kenny Construction Ltd | Construction | 2022 |
| J Nicholson & SON Limited | Real estate | 2014 |
| J T Roofing Limited | Construction | 2008 |
| J. E. White Motors Limited | Administrative & support | 2017 |
| J.Lewis Properties Ltd | Real estate | 2025 |
| Jack Ezra Designs Limited | Wholesale & retail | 2021 |
| Jaka Plumbing Ltd | Construction | 2020 |
| Jamark Developments Ltd | Construction | 2024 |
| Jamie Fisher Properties Ltd | Real estate | 2024 |
| Jarman Way Management Company Limited | Households | 1993 |
| Jasmine Gardens Private Ltd | Health & social care | 2018 |
| Jasmine House Investments Limited | Information & communication | 2024 |
| Jasper Road Management Limited | Households | 1983 |
| JB Squared Ltd | Wholesale & retail | 2010 |
| JBC21 Limited | Construction | 2026 |
| JD Building Services Hire & Sales Ltd | Administrative & support | 2015 |
| Jenpro Gwer Limited | Wholesale & retail | 2012 |
| JG & M Limited | Financial services | 2009 |
| Jigsaw Precision Joinery Limited | Manufacturing | 2010 |
| Jiyan Bozo Co. Ltd | Agriculture & fishing | 2025 |
| JLS Security Ltd | Construction | 2026 |
| JM Recovery Ltd | Wholesale & retail | 2013 |
| JMB Direct Ltd | Wholesale & retail | 2024 |
| JMB Property Solutions Ltd | Real estate | 2018 |
| Jogratia Ltd | Professional & scientific | 2026 |
| John's Fencing Ltd | Construction | 2021 |
| Joseph Anthony Investments Ltd | Real estate | 2024 |
| Joshuathomas Ltd | Wholesale & retail | 2003 |
| Jovan Consultants Limited | Professional & scientific | 2004 |
| Joyce Green Management Company Limited | Households | 2003 |
| Jrlandscapes and Tree Surgery Limited | Administrative & support | 2025 |
| JSP Logistics Solutions Ltd | Transport & logistics | 2018 |
| JTR London Investments Ltd | Real estate | 2025 |
| Juice Creative Limited | Manufacturing | 1999 |
| Just Cctv Ltd | Administrative & support | 1997 |
| Just Media Limited | Administrative & support | 2018 |
| Justone Consultancy Ltd | Professional & scientific | 2004 |
| JWP Estates Limited | Real estate | 2020 |
| K & C Trading Limited | Real estate | 2001 |
| K.Russell Contracts Ltd | Construction | 2021 |
| Kate Smith Conveyancing Ltd | Professional & scientific | 2015 |
| Kavanagh Court (Freehold) Limited | Households | 2021 |
| Kays Administrative Bureau Ltd | Administrative & support | 2022 |
| KB Property and Estate Management Ltd | Real estate | 2016 |
| KEH Construction Services Limited | Construction | 2012 |
| Kelly Plant & Haulage Limited | Construction | 2026 |
| Kelson Homes Ltd | Construction | 2019 |
| Keystone Investment (UK) LLP | | 2012 |
| KG Equestrian Limited | Agriculture & fishing | 2025 |
| KGH Property Restoration Ltd | Construction | 2024 |
| Kinfauns Road (Block D) Management Company Limited | Households | 1992 |
| Kingsway Electrical Services Limited | Construction | 2016 |
| Kingswood Assets Limited | Other services | 2017 |
| Kingswood Contractors Ltd | Construction | 2018 |
| Kinkaid Ltd | Construction | 2018 |
| Kirlide Trading & Investments Limited | Real estate | 1978 |
| Kitchen and Bathroom Makeovers Ltd | Wholesale & retail | 2026 |
| Kitchen Design Essex Limited | Construction | 2019 |
| Knight Street Freehold Management Company Limited | Administrative & support | 2018 |
| Knight Street Vault Ltd | Real estate | 2023 |
| Knights Kitchens Limited | Construction | 2021 |
| Knockalla Ltd | Real estate | 2015 |
| Knowl Piece Management Company Limited | Real estate | 1990 |
| KSV28 Ltd | Hospitality | 2025 |
| KTR Techywrite Ltd | Education | 2026 |
| Kwgh International Ltd | Professional & scientific | 2024 |
| L a Millane Ltd | Health & social care | 2019 |
| L R S Carpentry Ltd | Construction | 2012 |
| L&E Holdings Ltd | Financial services | 2025 |
| L.F. Properties (London) Limited | Real estate | 2003 |
| LA Fontaine London Ltd | Other services | 2022 |
| Labbman Limited | Transport & logistics | 2025 |
| Lady Sponge Fingers Ltd | Hospitality | 2010 |
| Lama Properties Ltd | Real estate | 2024 |
| Lamco Construction Services Ltd | Administrative & support | 2022 |
| Lancaster Lets Limited | Real estate | 2025 |
| Lancasters Gardencare Ltd | Administrative & support | 2019 |
| Land Sheriffs Limited | Administrative & support | 2006 |
| Landrews AV Ltd | Construction | 2022 |
| Larox Limited | Other services | 2017 |
| Later Life Legals Limited | Professional & scientific | 2019 |
| Launceston Gate (Epping) Management Company Limited | Administrative & support | 2004 |
| Lavender Hill Clothing Ltd | Manufacturing | 2013 |
| Lawd Limited | Construction | 2019 |
| Laytom Group Holdings Ltd | Financial services | 2026 |
| Laytom Property Management Ltd | Real estate | 2026 |
| Laytom SA Investments Ltd | Real estate | 2026 |
| Lbeautie Ltd | Wholesale & retail | 2018 |
| Leading Edge International Limited | Other services | 2000 |
| Learmonth & Co. Limited | Professional & scientific | 2006 |
| Leat Close Management Association Limited | Hospitality | 1978 |
| LEE Harris Electrical Ltd | Construction | 2017 |
| Lees Manor Court Management Limited | Households | 1985 |
| Leeward Property's Ltd | Real estate | 2024 |
| Legate Ltd | Transport & logistics | 2019 |