| JAM Investment Properties Ltd | Real estate | 2021 |
| JAM Media Engineering Limited | Information & communication | 2006 |
| Jama Property Limited | Real estate | 2022 |
| Jamadar and Krishnaa Holdings Limited | Hospitality | 2024 |
| Jamal M&E Services Ltd | Construction | 2019 |
| Jamali Consultancy Ltd | Professional & scientific | 2019 |
| Jaman Marketing Ltd | Manufacturing | 2025 |
| Jamat Limited | Hospitality | 2008 |
| Jamatek Ltd | Professional & scientific | 2021 |
| Jambi Estates Ltd | Real estate | 2024 |
| Jambo Media Group Ltd | Information & communication | 2009 |
| Jambox Self Storage Limited | Transport & logistics | 2022 |
| Jameela Healthcare PVT Ltd | Health & social care | 2014 |
| Jameela Homes PVT Ltd | Households | 2025 |
| James & Jenkins Garages Limited | Wholesale & retail | 1985 |
| James and Daughters Limited | Financial services | 2017 |
| James and Natasha Ansell Ltd | Health & social care | 2021 |
| James and Stoddart Property Services Ltd | Real estate | 2025 |
| James Bond 007 | Administrative & support | 2020 |
| James Brailey Limited | Wholesale & retail | 2007 |
| James Bricklaying Contractors Limited | Construction | 2019 |
| James Clatworthy Limited | Financial services | 2024 |
| James Colcombe Limited | Health & social care | 2015 |
| James Court Estates Limited | Construction | 1996 |
| James Edward Associates Limited | Information & communication | 2019 |
| James Edwards Properties Ltd | Real estate | 2020 |
| James Frazer Property Ltd | Real estate | 2020 |
| James Godsall & Sons Limited | Wholesale & retail | 1962 |
| James Henry Flat Roofing Limited | Construction | 2022 |
| James Horwell Limited | Construction | 2018 |
| James Jervis Partnership Ltd | Professional & scientific | 2010 |
| James John Lovell Ltd | Arts & recreation | 2015 |
| James Khan Ltd | Professional & scientific | 2021 |
| James King Architects Ltd | Professional & scientific | 2018 |
| James Lovelock Film Ltd | Information & communication | 2022 |
| James Mark Hayden Limited | Arts & recreation | 2017 |
| James Marr Limited | Agriculture & fishing | 2016 |
| James Murphy Groundworks Ltd | Construction | 2019 |
| James Plumbing & Heating Solutions Ltd | Construction | 2012 |
| James Rail Ltd | Construction | 2016 |
| James Robert Hemsley Limited | Manufacturing | 2025 |
| James Ruth Ltd | Information & communication | 2025 |
| James Spinks Ltd | Information & communication | 2020 |
| James Vincent Properties Limited | Real estate | 2021 |
| James Warner Inc Ltd | Information & communication | 2014 |
| Jamesdeantech Limited | Wholesale & retail | 2025 |
| Jamesfield Trading PC | | 2015 |
| Jamesllewis Ltd | Arts & recreation | 2021 |
| Jameson Trade Ltd | Wholesale & retail | 2025 |
| James’ Learning and Development Services Limited | Professional & scientific | 2021 |
| Jamezoen Co., Ltd | Extraterritorial | 2021 |
| Jamform Limited | Health & social care | 2007 |
| Jamia Properties Limited | Real estate | 2014 |
| Jamie Burley Flat Roofing Specialist Limited | Construction | 2014 |
| Jamie Cottington Ltd | Wholesale & retail | 2024 |
| Jamiescarsauto Limited | Wholesale & retail | 2024 |
| Jammac Canterbury Ltd | Hospitality | 2016 |
| Jamo Group Limited | Health & social care | 2018 |
| Jamo Limited | Information & communication | 2025 |
| Jams Cars Limited | Wholesale & retail | 2018 |
| Jamsow Limited | Wholesale & retail | 2022 |
| Jamtasticpunch Ltd | Administrative & support | 2016 |
| Jamuhu Ltd | Health & social care | 2014 |
| Jamuna (Wales) Limited | Hospitality | 2013 |
| JAN Barbers Cardiff Ltd | Other services | 2025 |
| JAN Star 66 Ltd | Other services | 2025 |
| Jan.D Works Ltd | Wholesale & retail | 2020 |
| Jana Moon Ltd | Extraterritorial | 2023 |
| Jana Properties Limited | Real estate | 2024 |
| Janata Palace Ltd | Hospitality | 2022 |
| Janderson PUB Co Ltd | Hospitality | 2024 |
| Jane Beauty Ltd | Other services | 2015 |
| Jane Consultancy BFD Ltd | Manufacturing | 2022 |
| Janelle International Limited | Other services | 2015 |
| Janellen Ltd | Professional & scientific | 2021 |
| Janet Flint Ltd | Wholesale & retail | 2025 |
| Janet's Ancestry Research Limited | Arts & recreation | 2017 |
| Janeys Jewellery Limited | Wholesale & retail | 2025 |
| Janine Holley Coaching Limited | Administrative & support | 2021 |
| Janis Fashion Limited | Wholesale & retail | 2025 |
| Jannat Sarees Limited | Wholesale & retail | 2018 |
| Jansen Trading Ltd | Wholesale & retail | 2025 |
| Janset Trade Ltd | Wholesale & retail | 2026 |
| Jantaj Ltd | Health & social care | 2019 |
| January Tech Ltd | Information & communication | 2021 |
| JAP Rail Ltd | Construction | 2018 |
| JAP Trade Direct Ltd | Wholesale & retail | 2025 |
| Japan Seiwa Kampo Co., Ltd | Mining & quarrying | 2025 |
| Japan Zuoye Zhushihuishe Share Ltd | Extraterritorial | 2021 |
| Japancrafts Trading Limited | Information & communication | 2026 |
| Japonica Services Ltd | Professional & scientific | 2012 |
| Japs Sanz Limited | Information & communication | 2025 |
| Jaqh Ltd | Wholesale & retail | 2017 |
| JAR Jennifer Home Furnishings Limited | Wholesale & retail | 2024 |
| JAR Site Solutions Ltd | Administrative & support | 2017 |
| Jare Holdings Ltd | Other services | 2022 |
| Jareda Capital Limited | Financial services | 2025 |
| Jareda Holdings Limited | Financial services | 2025 |
| Jarfen Ltd | Wholesale & retail | 2024 |
| Jarso Fire Protection Ltd | Public administration | 2023 |