| J & Co Partners Limited | Real estate | 2023 |
| J & H Sales (International) Limited | Water & waste | 1990 |
| J & J Health Foods Ltd | Wholesale & retail | 2022 |
| J & J Housing Limited | Real estate | 2002 |
| J & M Fashion Limited | Manufacturing | 2007 |
| J & N Manji Properties Limited | Construction | 2019 |
| J & R Food and Wine Limited | Wholesale & retail | 2009 |
| J & RK Ltd | Professional & scientific | 2024 |
| J & S Assets Limited | Real estate | 2023 |
| J & T Builders Limited | Construction | 2012 |
| J a Malathi Ltd | Hospitality | 2025 |
| J a Property Maintenance Limited | Construction | 2024 |
| J and D Payroll Services Limited | Other services | 2019 |
| J and Z Traders Ltd | Wholesale & retail | 2024 |
| J B Executive Support Ltd | Administrative & support | 2019 |
| J BAL Properties Limited | Households | 2023 |
| J Banu Roofing Ltd | Construction | 2025 |
| J Bradley Ductwork Limited | Construction | 2008 |
| J C Heating and Building Services Limited | Construction | 2010 |
| J C Midas Design Ltd | Construction | 2014 |
| J Commerce Retail Ltd | Wholesale & retail | 2026 |
| J Construction Building Services Limited | Construction | 2021 |
| J Cook & Sons Limited | Construction | 2010 |
| J Dale Therapists Limited | Other services | 2015 |
| J Fricker Tiling Limited | Construction | 1997 |
| J Home Improvements Ltd | Construction | 2015 |
| J Hutton Real Estate Ltd | Real estate | 2021 |
| J J Construction London Ltd | Construction | 2023 |
| J J Productions & Entertainment Ltd | Arts & recreation | 2023 |
| J Jno-Baptiste Contracts Limited | Construction | 2006 |
| J K Claire Developments Ltd | Real estate | 2023 |
| J K Shah Accountants Ltd | Professional & scientific | 2016 |
| J K Surfacing (UK) Ltd | Construction | 2012 |
| J L R Gold Bookkeeping Services Ltd | Professional & scientific | 2025 |
| J Marshall Roofing (London) Ltd | Construction | 2023 |
| J Nelson Consultancy Limited | Administrative & support | 2015 |
| J P Builders (Essex) Ltd | Construction | 2020 |
| J P PAN Centre Limited | Wholesale & retail | 2019 |
| J Prestige Wholesale Limited | Wholesale & retail | 2017 |
| J Properties London Ltd | Real estate | 2022 |
| J R Grimes Limited | Construction | 2014 |
| J Rice Plumbing & Heating Ltd | Construction | 2024 |
| J S Aston & Co Limited | Professional & scientific | 2018 |
| J S Building Works Limited | Construction | 2025 |
| J S Corporation Ltd | Wholesale & retail | 2014 |
| J S Haider Holding Ltd | Financial services | 2026 |
| J S J Food and Wine Ltd | Wholesale & retail | 2018 |
| J S Maintenance and Solutions Ltd | Manufacturing | 2021 |
| J S Mann Limited | Construction | 2019 |
| J S Painters & Decorators Limited | Construction | 2022 |
| J S Pharma Limited | Wholesale & retail | 2018 |
| J S Thandi Ltd | Health & social care | 2022 |
| J Saimon & Co Limited | Hospitality | 2020 |
| J Saimon Law Ltd | Professional & scientific | 2020 |
| J Sangha Ltd | Health & social care | 2025 |
| J Service Properties Ltd | Real estate | 2018 |
| J Singh Maintenance Limited | Construction | 2024 |
| J T Reno Limited | Hospitality | 2009 |
| J Thompson Builders Limited | Construction | 2009 |
| J Uddin Consulting Ltd | Professional & scientific | 2023 |
| J W Auto Group Limited | Wholesale & retail | 2024 |
| J W Investments Ltd | Real estate | 2019 |
| J W Kelly Limited | Construction | 1994 |
| J W Kelly Properties Ltd | Real estate | 2023 |
| J White Interiors Limited | Construction | 2008 |
| J&A Realty Ltd | Real estate | 2025 |
| J&B Couriers Limited | Transport & logistics | 2024 |
| J&F Builders Ltd | Construction | 2023 |
| J&H Living Ltd | Real estate | 2020 |
| J&J Global Construction Ltd | Construction | 2024 |
| J&J Kitchen and Bedrooms Ltd | Manufacturing | 2025 |
| J&J Tech Ltd | Information & communication | 2019 |
| J&M Cupcakes Ltd | Arts & recreation | 2026 |
| J&M Security Company Limited | Administrative & support | 2015 |
| J&N Metals Ltd | Wholesale & retail | 2021 |
| J&S Plumbing & Heating Limited | Construction | 2018 |
| J&Y Love Ltd | Hospitality | 2022 |
| J'S LDN Ltd | Hospitality | 2021 |
| J,S,S Electrical Limited | Manufacturing | 2022 |
| J-H Deesert Ltd | Hospitality | 2025 |
| J-Webs Trading AS J-Webs Limited | Construction | 2025 |
| J. Brati Construction Limited | Construction | 2017 |
| J. Scott & Sons Limited | Manufacturing | 1978 |
| J.A.E Brickwork Limited | Construction | 2024 |
| J.B Valeting Ipswich Ltd | Wholesale & retail | 2022 |
| J.C.B. Engineering Company Limited | | 1957 |
| J.C.Ceilings Ltd | Construction | 2026 |
| J.H. Interiors Limited | Construction | 1998 |
| J.K Cosmetics Ltd | Wholesale & retail | 2025 |
| J.Khan's World Ltd | Wholesale & retail | 2025 |
| J.Lettings Limited | Real estate | 2013 |
| J.M.D (Bhumi) Ltd | Real estate | 2025 |
| J.Mays Construction Ltd | Construction | 2015 |
| J.P.C. Electrical Wholesalers (Woodford) Limited | Wholesale & retail | 1976 |
| J.P.M. Flooring Limited | | 1987 |
| J.S.M Solutions Ltd | Information & communication | 2016 |
| J.W.B. Investments (UK) Ltd | Real estate | 2014 |
| J2 Nail Creative Ltd | Other services | 2025 |
| J3 Business Consultancy Ltd | Professional & scientific | 2019 |
| J3 Infotech Services Ltd | Information & communication | 2022 |