| J & a Sutherland Limited | Professional & scientific | 2018 |
| J C Electrics (Cranleigh) Limited | Financial services | 2023 |
| J C Electrics (Guildford) Limited | Financial services | 2011 |
| J C Flooring Services (2021) Limited | Construction | 2021 |
| J C H Rail Limited | Transport & logistics | 2018 |
| J C S Codicote Limited | Professional & scientific | 2018 |
| J Gonzalez Ventures Group Ltd | Financial services | 2023 |
| J H Hart & Co LLP | | 2011 |
| J Harris Carpentry Limited | Construction | 2021 |
| J R C Estates Limited | Construction | 2006 |
| J Riley Carpentry Ltd | Construction | 2014 |
| J S Property Group Limited | Real estate | 2016 |
| J Searle Contractors Limited | Construction | 2022 |
| J&H Toy Vault Ltd | Wholesale & retail | 2025 |
| J-Curve Properties Limited | Professional & scientific | 2024 |
| J. P. Wearing & Co Limited | Professional & scientific | 2001 |
| J.E. Trimming (Builders) Limited | Construction | 1960 |
| J.E.F Fabrications Ltd | Construction | 2024 |
| J.G. Regan Limited | Professional & scientific | 1985 |
| J.M. Rush & Co. Limited | Real estate | 1984 |
| J.M.L. Consultants UK Limited | Administrative & support | 1998 |
| J.Pavey Holdings One Ltd | Professional & scientific | 2021 |
| J.Pavey Holdings Two Ltd | Information & communication | 2021 |
| J.Y. Limited | Professional & scientific | 2005 |
| J2 Interactive Solutions Ltd | Information & communication | 2012 |
| JA Projects Ltd | Administrative & support | 2022 |
| Jabro Food & Drinks (Luton) Limited | Transport & logistics | 1990 |
| Jack Finnis Apps Limited | Information & communication | 2025 |
| Jack Hilder Property Group Ltd | Construction | 2025 |
| Jack Meadows Bespoke Joinery Ltd | Manufacturing | 2024 |
| Jack Whelan Homes Limited | Real estate | 2003 |
| Jackam Limited | Professional & scientific | 2020 |
| Jackson Animal Care Services Ltd | Professional & scientific | 2023 |
| Jackson Bar Franchise Ltd | Hospitality | 2023 |
| Jacobs House Management Limited | Households | 2014 |
| Jadow Properties Limited | Real estate | 2025 |
| Jafor SUB Ltd | Hospitality | 2016 |
| Jaivir Limited | Wholesale & retail | 2022 |
| Jake Bryan Dennis Limited | Extraterritorial | 2024 |
| Jaluto Investments Ltd | Real estate | 2019 |
| James Chew Limited | Construction | 2014 |
| James Elaine Ltd | Real estate | 2021 |
| James Harwood Ltd | Professional & scientific | 2014 |
| James Hilton Limited | Professional & scientific | 2014 |
| James Spice Human Development Limited | Other services | 2021 |
| Jamieowen Corp Ltd | Professional & scientific | 2024 |
| Jams Consulting Limited | Information & communication | 2025 |
| Jamworks Platform Limited | Information & communication | 2020 |
| Jana Lewis Ltd | Other services | 2013 |
| Jane Dixon Coaching & Consulting Ltd | Professional & scientific | 2025 |
| Jane Wonnacott Safeguarding Consultancy Limited | Education | 2015 |
| Jansons Consulting Ltd | Other services | 2024 |
| Jasmine Valentine Ltd | Wholesale & retail | 2025 |
| Jaston Technical Ltd | Information & communication | 2013 |
| Jato Group Limited | Information & communication | 2022 |
| Java Projects Limited | Real estate | 2024 |
| JAY Ganesh Limited | Real estate | 2021 |
| Jayne Coles Limited | Hospitality | 2019 |
| Jazz Revelations Ltd | Information & communication | 2020 |
| JB Hospitality Services Ltd | Hospitality | 2025 |
| Jbgb Limited | Real estate | 2019 |
| JC Content Strategies Ltd | Professional & scientific | 2021 |
| Jc's Fruit & VEG Ltd | Wholesale & retail | 2020 |
| Jchms Limited | Real estate | 2014 |
| JD Simpson (Marine) Limited | Extraterritorial | 2008 |
| JDC Focus Physio Ltd | Health & social care | 2026 |
| JDS Drainage Ltd | Construction | 2023 |
| JE Architecture Limited | Professional & scientific | 2013 |
| Jean Graham Salons Limited | Extraterritorial | 1981 |
| JEB Wholesales Limited | Wholesale & retail | 2021 |
| Jedz Ltd | Wholesale & retail | 2018 |
| Jeem Media Ltd | Information & communication | 2018 |
| Jeff IT Services Limited | Information & communication | 2008 |
| Jeff Ward Limited | Information & communication | 2017 |
| Jeggo Ltd | Information & communication | 2025 |
| Jenkins & Falvey Limited | Construction | 2014 |
| Jenks and Co. Ltd | Information & communication | 2004 |
| Jennyfields Home Improvements Ltd | Manufacturing | 2015 |
| Jennyfields Installations Ltd | Extraterritorial | 2015 |
| Jennyfields Window Specialists Ltd | Manufacturing | 2015 |
| Jerusalem and the East Mission Trust,Limited(The) | Other services | 1929 |
| Jesse Engelbrecht Squash Academy Limited | Arts & recreation | 2010 |
| Jessica Godesen Events Ltd | Administrative & support | 2019 |
| JF Mortgage Services Limited | Administrative & support | 2019 |
| JF Surrey Limited | Hospitality | 2017 |
| JG Co-Living Spaces Ltd | Real estate | 2023 |
| JG Conversions Ltd | Real estate | 2023 |
| JG Letting Ltd | Extraterritorial | 2023 |
| JG Service Accommodation Ltd | Hospitality | 2023 |
| JGF Machinery Limited | Manufacturing | 2005 |
| JH Secretarial Services Ltd | Administrative & support | 2021 |
| Jigsaw Electrical Services Ltd | Construction | 2025 |
| JIGSAW97 Limited | Administrative & support | 2011 |
| JJB Couriers Ltd | Transport & logistics | 2026 |
| JJL Property Ltd | Households | 2005 |
| JK Wilson Architects Ltd | Professional & scientific | 2023 |
| Jkjsm Ltd | Administrative & support | 2016 |
| JLM Bespoke Furniture Limited | Manufacturing | 2014 |
| JLS Mediation Limited | Professional & scientific | 2011 |
| JLV Holidays Limited | Real estate | 2026 |