| JHR Bathrooms and Plumbing Ltd | Construction | 2020 |
| JHS Logistics Ltd | Transport & logistics | 2016 |
| JIC Partnership Limited | Education | 2016 |
| Jigsaw Early Years Consultancy Ltd | Education | 2018 |
| Jimjam Holdings Limited | Information & communication | 2023 |
| JJ Apparels Ltd | Wholesale & retail | 2024 |
| JJ Panj Ltd | Financial services | 2022 |
| JJH Electrical Services Ltd | Manufacturing | 2019 |
| Jjro Merchandising Ltd | Administrative & support | 2024 |
| JKM Surveying & Estimating Ltd | Professional & scientific | 2020 |
| JL Carpentry Ltd | Manufacturing | 2021 |
| JLD Estates Limited | Real estate | 2021 |
| JLE Testing Ltd | Administrative & support | 2015 |
| JLM Richards Ltd | Real estate | 2024 |
| Jlms Management Ltd. | Education | 2013 |
| Jlms Properties Ltd | Construction | 2022 |
| JM Baker Property Ltd | Real estate | 2025 |
| JM Postal SYS Limited | Transport & logistics | 2020 |
| JM3 Holdings Limited | Financial services | 2025 |
| JM3 Warsash Road Limited | Construction | 2025 |
| JMC Building Services Ltd | Construction | 2019 |
| Jmikings Ltd | Other services | 2023 |
| JMN Construction Limited | Construction | 1999 |
| JMP Anderson & Associates Limited | Financial services | 2013 |
| JMP Estimation Limited | Professional & scientific | 2025 |
| JMP Finance Limited | Wholesale & retail | 2024 |
| Jmrl Properties Limited | Real estate | 2024 |
| JMS Building & Maintenance Limited | Construction | 2008 |
| JNM Electrical Engineering Ltd | Construction | 2025 |
| JNR Garden Services Ltd | Administrative & support | 2021 |
| JNR Property Ltd | Real estate | 2022 |
| JNS Designs Limited | Administrative & support | 2012 |
| JNS Enterprises Limited | Real estate | 2024 |
| JO Erin Yates Ltd | Information & communication | 2023 |
| Jobable Solutions Ltd | Information & communication | 2024 |
| Jocund Ltd | Financial services | 2022 |
| Jodan Bator Limited | Transport & logistics | 2024 |
| JOE Savage Garden Design Ltd | Administrative & support | 2022 |
| Joeglow Services Ltd | Construction | 2013 |
| Joel Blois Limited | Information & communication | 2015 |
| Joesh Group Limited | Real estate | 2022 |
| Joesh R1 Ltd | Real estate | 2022 |
| Joesh R10 Ltd | Real estate | 2022 |
| Joesh R2 Ltd | Real estate | 2022 |
| Joesh R3 Ltd | Real estate | 2022 |
| Joesh R4 Ltd | Real estate | 2022 |
| Joesh R5 Ltd | Real estate | 2022 |
| Joesh R6 Ltd | Real estate | 2022 |
| Joesh R7 Ltd | Real estate | 2022 |
| Joesh R8 Ltd | Real estate | 2022 |
| Joesh R9 Ltd | Real estate | 2022 |
| Joesh Residential Limited | Real estate | 2022 |
| Joginn Limited | Hospitality | 2023 |
| John Konig & Co Limited | Wholesale & retail | 1986 |
| John Marsh Properties Limited | Construction | 2025 |
| John O'Gaunt Fishery Limited | Arts & recreation | 2000 |
| John Penny Restoration Limited | Extraterritorial | 2003 |
| John Reilly (Civil Engineering) Limited | Construction | 1986 |
| John William Roberts Limited | Financial services | 2007 |
| Johnson Papertech Ltd | Professional & scientific | 2024 |
| Johnson Teque Consulting Ltd | Extraterritorial | 2024 |
| JON Callen Podiatry Limited | Health & social care | 2012 |
| JON Dale Architects Limited | Professional & scientific | 2007 |
| Jon's Garage Limited | Wholesale & retail | 2012 |
| Jonben Ltd | Health & social care | 2013 |
| Jonju Tech Ltd | Professional & scientific | 2020 |
| Jooash Enterprises Ltd | Transport & logistics | 2018 |
| Joselyn Secker Consulting Ltd | Professional & scientific | 2021 |
| Joss Engineering Solutions Limited | Professional & scientific | 2015 |
| Joss Legal Solutions Limited | Professional & scientific | 2015 |
| Joss Mooney Limited | Other services | 2016 |
| Journeys Through Sound Ltd | Health & social care | 2022 |
| Jpaldi Tech Limited | Information & communication | 2026 |
| JPF Sligo Holdings Limited | Wholesale & retail | 2017 |
| Jpmc.Consultancy Ltd | Information & communication | 2025 |
| JPS Fallon Limited | Construction | 2022 |
| JPS Fire & Security Limited | Construction | 1994 |
| JPS Hampshire Ltd | Financial services | 2022 |
| JPS Scaffolding Limited | Construction | 2007 |
| JRB Financial Services Limited | Professional & scientific | 2022 |
| Jrbs Southern Limited | Construction | 2019 |
| JRC BIM Ltd | Construction | 2024 |
| JRC Integral Properties Limited | Real estate | 2021 |
| JRG Plumbing & Heating Limited | Construction | 2015 |
| Jrifvic Care Services Limited | Information & communication | 2019 |
| JS Chiropractic Limited | Health & social care | 2022 |
| JS Parade Ltd | Wholesale & retail | 2021 |
| JSC10 Ltd | Real estate | 2017 |
| JSK Financial Investments Ltd | Real estate | 2018 |
| Jsla Food Ltd | Hospitality | 2026 |
| JSP Carpentry & Joinery Ltd | Manufacturing | 2024 |
| JTC Homes Ltd | Real estate | 2024 |
| JTM Autos Limited | Wholesale & retail | 2016 |
| JTR Pensions & Benefit Management Ltd. | Financial services | 2000 |
| Jubilee Endoscopy (Hampshire) Limited | Health & social care | 2013 |
| Judgement Spine Limited | Professional & scientific | 2026 |
| Judges Gully Management Limited | Households | 1994 |
| Junction 13 Eastleigh | Other services | 2012 |
| Jurassic Coast BJJ Ltd | Other services | 2021 |
| Jusashoot Network Ltd | Information & communication | 2025 |