| J.E.M Welding Limited | Professional & scientific | 2025 |
| J.H. Mechanical Engineering Services Ltd | Extraterritorial | 2013 |
| J.Knight and SON Limited | Transport & logistics | 2017 |
| J.L.H Mechanical Limited | Construction | 2018 |
| J.R. Printing Services Limited | Manufacturing | 1995 |
| J.R.C. Shops Limited | Real estate | 2011 |
| J.Reid Building Services Ltd | Construction | 2022 |
| J.S Painting and Decorating Ltd | Construction | 2025 |
| J.S.K Brickwork & Landscaping Limited | Construction | 2025 |
| J.Walker Building & Construction Ltd | Construction | 2021 |
| J.Walls Roofing Ltd | Construction | 2023 |
| J2B Consulting Ltd | Professional & scientific | 2025 |
| Jaag Consultancy Ltd | Information & communication | 2026 |
| Jack Lamonby Ltd | Real estate | 2019 |
| Jack's Place Dogboarding Ltd | Administrative & support | 2017 |
| Jackson & James Home Improvements Ltd | Construction | 2024 |
| Jackson Group Construction Ltd | Construction | 2022 |
| Jackson Till Drylining Ltd | Construction | 2026 |
| Jacksonville Consulting Ltd | Real estate | 2025 |
| Jacob Homes (Southern) Ltd | Real estate | 2019 |
| Jacqui Marie Photography Ltd | Professional & scientific | 2015 |
| Jacuzzui Club International Limited | Financial services | 2020 |
| JAD Property Services Limited | Construction | 2015 |
| Jade Procurement Services Limited | Information & communication | 2006 |
| Jadlt Limited | Real estate | 2024 |
| Jahan Geer Habib Ltd | Wholesale & retail | 2024 |
| Jake Dillon Cybersecurity Services Ltd | Information & communication | 2022 |
| Jaltco Limited | Real estate | 2003 |
| James & Stewart Roofing Limited | Construction | 2007 |
| James Demolition Ltd | Real estate | 2014 |
| Jamie Brown Carpentry Ltd | Manufacturing | 2024 |
| Jamie Wells Property Maintenance Ltd | Construction | 2026 |
| Jane's Patisserie Ltd | Information & communication | 2019 |
| Janet and Travis Properties Limited | Real estate | 2023 |
| Jane’S Patisserie Bakes LLP | | 2025 |
| Jannah Foods Ltd | Manufacturing | 2025 |
| Janoran Ltd | Wholesale & retail | 2025 |
| Janssen Flowers Ltd | Wholesale & retail | 2019 |
| Jarccs Limited | Extraterritorial | 2024 |
| Jardar Limited | Information & communication | 2025 |
| Jarvis Scaffolding Services Limited | Construction | 2024 |
| Jasmond OIL & Marketing Ltd | Other services | 2017 |
| Jaszara Aesthetics Limited | Health & social care | 2025 |
| Javelin Controls Limited | Construction | 2013 |
| JAY Ralls Electrics Ltd | Manufacturing | 2025 |
| JAY Ralls Engineering Limited | Manufacturing | 2019 |
| Jay's Barbers Limited | Other services | 2003 |
| Jayes Property Ltd | Real estate | 2019 |
| Jaynath Healthcare Ltd | Health & social care | 2024 |
| Jaytal Logistics Ltd | Transport & logistics | 2018 |
| Jazalea Ltd | Hospitality | 2023 |
| Jazz Rawlins Hair & Beauty Ltd | Other services | 2026 |
| JB Carpentry (Southern) Ltd | Construction | 2022 |
| JB French Houses Limited | Real estate | 2002 |
| JB Hatherley Builders & Decorators Ltd. | Construction | 1998 |
| JB Hospitality Ltd | Arts & recreation | 2020 |
| JB Motor Co (UK) Ltd | Wholesale & retail | 2019 |
| JB Plumbing N Heating Limited | Construction | 2015 |
| JB Salvage Limited | Wholesale & retail | 2018 |
| JB Steels & Construction Ltd | Construction | 2020 |
| JB Water Consulting Limited | Professional & scientific | 2026 |
| JB Web Limited | Information & communication | 2014 |
| JB Window Cleaning Hampshire Ltd | Administrative & support | 2023 |
| JBA Plumbing & Heating Limited | Construction | 2011 |
| JBP Southern Limited | Real estate | 2020 |
| JBR Collection Limited | Wholesale & retail | 2024 |
| JBS Accountancy Ltd | Professional & scientific | 2023 |
| JBS Containers Ltd | Transport & logistics | 2023 |
| JBS Heating & Plumbing Ltd | Construction | 2025 |
| JBS Yard Ltd | Other services | 2014 |
| Jbsc Properties Limited | Real estate | 2024 |
| JBT Pharmaceutical Services Ltd | Health & social care | 2016 |
| JC Direct Plumbing and Heating Ltd | Construction | 2018 |
| JC Direct Properties Ltd | Real estate | 2023 |
| JC Management and Concultancy Services Ltd | Construction | 2021 |
| JC Oncology Ltd | Health & social care | 2022 |
| JC Plant (Southern) Ltd | Administrative & support | 2017 |
| JC Toast Limited | Real estate | 2013 |
| Jcctiling Ltd | Construction | 2026 |
| Jcdp Limited | Professional & scientific | 2010 |
| JCI Property Limited | Real estate | 2020 |
| JCL Clinical Services Limited | Health & social care | 2022 |
| JCP (South) Ltd | Construction | 2018 |
| Jcse Design (Chichester) Limited | Professional & scientific | 2022 |
| Jcse Design Ltd | Professional & scientific | 2022 |
| Jcse Ltd | Professional & scientific | 2017 |
| JD Hill Holdings Ltd | Financial services | 2023 |
| JD Marine Ltd | Construction | 2021 |
| JD Roofing & Cladding Ltd | Construction | 2021 |
| JDC Facility Ltd | Extraterritorial | 2019 |
| Jdconstructionportsmouth Limited | Construction | 2013 |
| JDD Developments Ltd | Real estate | 2020 |
| JDF Builders Ltd | Construction | 2026 |
| JDI Fire Protection Limited | Construction | 2024 |
| JDI Projects Holdings Limited | Professional & scientific | 2024 |
| JDI Projects Limited | Construction | 2019 |
| JDI Property Investments Ltd | Real estate | 2020 |
| JDM Spec Ltd | Manufacturing | 2014 |
| JDS Industries Ltd | Wholesale & retail | 2016 |
| JDW Groundworks Southern Ltd | Construction | 2026 |