| J H Green Consultancy Limited | Professional & scientific | 2023 |
| J J a Smith Limited | Administrative & support | 2023 |
| J J Radford Plumbing & Property Maintenance Ltd | Construction | 2017 |
| J Lewis Plumbing & Heating Ltd | Construction | 2012 |
| J Metcalfe Landscapes Limited | Administrative & support | 2009 |
| J R S Aesthetics Ltd | Health & social care | 2026 |
| J Sheather Mortgages Ltd | Financial services | 2018 |
| J T Simmonds Roofing Ltd | Construction | 2024 |
| J&J Property Care Ltd | Administrative & support | 2025 |
| J&L Logan Ltd | Education | 2021 |
| J&R Family Holdings Ltd | Financial services | 2024 |
| J. & M. Garden Machinery Limited | Manufacturing | 1986 |
| J. Button & Co Limited | Financial services | 2002 |
| J. Jackson & Sons (Surrey) Limited | Wholesale & retail | 1995 |
| J.Cobb Limited | Professional & scientific | 1999 |
| J.Fishburn Building Contractor Limited | Construction | 2017 |
| J.H. Henderson & Sons (Television) Limited | Information & communication | 2003 |
| J.M. Construction and Developments Limited | Construction | 2008 |
| J.M.Harlow Limited | Real estate | 1931 |
| J.R. Close Management Limited | Extraterritorial | 2003 |
| J.W. Developers Limited | Real estate | 2005 |
| J2 Arms Limited | Health & social care | 2023 |
| Jack's Wood CIC | Other services | 2023 |
| Jackalberry Limited | Financial services | 2021 |
| Jackman’S Lodge Home Care Services Limited | Health & social care | 2019 |
| Jackmax Limited | Education | 2020 |
| Jackson Fine Art Ltd | Wholesale & retail | 2002 |
| Jacob and Jacob Heating Ltd | Construction | 2017 |
| Jacob and Jacob Limited | Construction | 2014 |
| Jacobs Global Holding Limited | Financial services | 2024 |
| Jacobs Green (Guildford) Management Company Limited | Households | 2015 |
| Jacobs Well Cafe Ltd | Hospitality | 2026 |
| JAG Capital Investments Limited | Financial services | 2022 |
| JAG Doctor Limited | Wholesale & retail | 2020 |
| Jagemoha Limited | Hospitality | 2017 |
| JAI (Global) Ltd | Professional & scientific | 2018 |
| Jakovlev Car Sharing Ltd | Transport & logistics | 2017 |
| Jakovlev Holding Ltd | Real estate | 2023 |
| Jamaican Heritage Renewal | Health & social care | 1997 |
| James Bailey Limited | Construction | 2013 |
| James Beard Consulting Ltd | Professional & scientific | 2022 |
| James Lynn Ltd | Education | 2020 |
| James of Shepperton Limited | Wholesale & retail | 2011 |
| James Upfold Construction Limited | Construction | 2009 |
| James Woods Trading Ltd | Wholesale & retail | 2022 |
| JAN Digital Limited | Professional & scientific | 2012 |
| Janat Estates Ltd | Real estate | 2021 |
| Jane Stevenson Communications Limited | Administrative & support | 2009 |
| Janiche Limited | Health & social care | 2023 |
| Janine Hawkins Limited | Professional & scientific | 2013 |
| Jantzen Consulting Ltd | Professional & scientific | 2016 |
| Japan Import Car Store UK Ltd | Wholesale & retail | 2023 |
| Jathub CIC | Professional & scientific | 2026 |
| Jaufacake Ltd | Real estate | 2026 |
| Javelin ID Limited | Wholesale & retail | 1998 |
| Jaws Consultancy Ltd | Administrative & support | 2010 |
| Jaws Real Estate Limited | Real estate | 2020 |
| Jaws Resources Limited | Construction | 2015 |
| Jaykay Consultants Limited | Professional & scientific | 2018 |
| Jaykay Project Management Limited | Professional & scientific | 2010 |
| Jazoan Properties Limited | Real estate | 2015 |
| JB Studio Ltd | Professional & scientific | 2020 |
| JBA Property Services Ltd | Real estate | 2019 |
| Jbll Services Ltd | Administrative & support | 2025 |
| Jcoa Limited | Construction | 2020 |
| JCS Associates Limited | Extraterritorial | 2017 |
| JD Property Consultancy Limited | Real estate | 2016 |
| JDC Electrical Engineers Limited | Construction | 2013 |
| Jdcateringgroup Ltd | Hospitality | 2025 |
| JDS Compressor Group Ltd | Financial services | 2024 |
| JDS Compressors Limited | Manufacturing | 2017 |
| JDS Decorations Limited | Construction | 2017 |
| JDS Guildford Ltd | Administrative & support | 2025 |
| Jdtrix Ltd | Administrative & support | 2023 |
| Jedi Systems Consultancy Limited | Information & communication | 2006 |
| Jeff Carroll Associates Limited | Professional & scientific | 2003 |
| Jellyfish Analytics Limited | Extraterritorial | 2024 |
| Jellytree Productions Limited | Information & communication | 1999 |
| Jemade Palmer Property Consultants Limited | Construction | 2019 |
| Jemade Palmer Property Maintenance Ltd | Extraterritorial | 2022 |
| Jemma Thompson Interiors Limited | Professional & scientific | 2018 |
| Jemrose Ltd | Administrative & support | 2020 |
| Jenner Hair Cosmetics Ltd | Other services | 2026 |
| Jenny Cooper Consultancy Limited | Professional & scientific | 2025 |
| Jent Property Ltd | Real estate | 2020 |
| Jeron Properties Ltd | Real estate | 2022 |
| Jesse Moran Ltd | Health & social care | 2019 |
| Jessica Limited | Real estate | 2026 |
| Jessop House Haslemere Management Company Limited | Households | 2006 |
| JET Pearl Limited | Real estate | 2016 |
| Jetbyte Limited | Information & communication | 1997 |
| Jetons Investments Ltd | Financial services | 2011 |
| JEZ Cartwright Limited | Professional & scientific | 2001 |
| JGH Plant Services Limited | Manufacturing | 2005 |
| JH Trading and Services Limited | Wholesale & retail | 2025 |
| Jhep Limited | Professional & scientific | 2010 |
| JHS Assets Ltd | Wholesale & retail | 2010 |
| JHW Investments Limited | Other services | 2017 |
| JID Technology Services Limited | Information & communication | 2017 |
| Jille Limited | Wholesale & retail | 2021 |