| IS4 Cryogenics Ltd | Professional & scientific | 2019 |
| Iskandar Holdings Ltd | Real estate | 2025 |
| Istanbul Barber Didcot Ltd | Other services | 2026 |
| IT and AV Services Limited | Information & communication | 2015 |
| ITB Holdings Ltd | Financial services | 2022 |
| IVY BLU Weddings Ltd | Other services | 2020 |
| Iwcam Invest Ltd | Real estate | 2024 |
| J & J Voltage Ltd | Construction | 2020 |
| J &J Assets Ltd | Real estate | 2023 |
| J B Delfosse Limited | Health & social care | 2013 |
| J S Greenough Plumbing & Heating Ltd | Construction | 2017 |
| J&F Living Spaces Ltd | Real estate | 2025 |
| J&M Allset Properties Ltd | Real estate | 2025 |
| J&M Prestige Care Ltd | Public administration | 2023 |
| J-Cog Solutions Ltd | Real estate | 2024 |
| Jacada Group Limited | Financial services | 2020 |
| Jackson Property Limited | Real estate | 2016 |
| Jacksons International Limited | Real estate | 2006 |
| Jacobs Education & Training Safety Ltd | Education | 2010 |
| Jadestone Assets Ltd | Real estate | 2022 |
| JAJ Property Ltd | Real estate | 2019 |
| Jake Burgess Films Ltd | Information & communication | 2018 |
| Jakmur Ltd | Real estate | 2017 |
| JAL Associates UK Limited | Construction | 2013 |
| James Basey Architects Ltd | Professional & scientific | 2024 |
| James Quayle Creative Limited | Information & communication | 2022 |
| James Russell Investments Ltd | Professional & scientific | 2023 |
| James Wanstall Ltd | Mining & quarrying | 2022 |
| Jamie Pursall Racing Limited | Manufacturing | 2022 |
| Jankos Limited | Transport & logistics | 2012 |
| Jayde Property & Co Ltd | Real estate | 2026 |
| Jazmas Ltd | Real estate | 2024 |
| JB Concepts Limited | Real estate | 2024 |
| JC Hawkins Ltd | Health & social care | 2024 |
| JCC Busarch Limited | Information & communication | 2016 |
| JCH Rutter Ltd | Real estate | 2025 |
| JCI Healthcare Ltd | Health & social care | 2026 |
| JCR Scaffolding Ltd | Construction | 2024 |
| JD Decorating & Property Maintenance Ltd | Construction | 2020 |
| Jenni Dawson Ceramics Ltd | Manufacturing | 2025 |
| Jgmc Consulting Ltd | Information & communication | 2024 |
| JGP Brickwork Ltd | Construction | 2015 |
| JGP Physiotherapy Ltd | Health & social care | 2024 |
| JH Resources Ltd | Administrative & support | 2023 |
| JHG Editorial Ltd | Information & communication | 2017 |
| JIC Direct Retail Ltd | Wholesale & retail | 2017 |
| Jigsaw Complete Building Projects Limited | Professional & scientific | 2007 |
| Jikelele Limited | Information & communication | 2025 |
| Jiya Technologies Ltd | Information & communication | 2018 |
| Jjbe Estates Ltd | Real estate | 2022 |
| JJS Holding Partners Ltd | Wholesale & retail | 2020 |
| JK Plastering Ltd | Construction | 2025 |
| JK White Logistics Ltd | Transport & logistics | 2020 |
| JKC Plastering Limited | Construction | 2025 |
| Joey Property Solutions Ltd | Construction | 2023 |
| Jofirisi Enterprise Limited | Health & social care | 2015 |
| John & Isabella Limited | Health & social care | 2017 |
| Johnson Racing Farriers Ltd | Agriculture & fishing | 2021 |
| Jolix Property Ltd | Real estate | 2025 |
| Jolly Good JOB Ltd | Administrative & support | 2011 |
| Jones Decorators (Didcot) Limited | Construction | 2016 |
| Jovi Entertainment Limited | Professional & scientific | 2023 |
| JP Fresh Creations Ltd | Wholesale & retail | 2019 |
| JP Fresh Global Investments Ltd | Financial services | 2021 |
| JR Motion Design Limited | Information & communication | 2013 |
| JR Portfolio Mgmt Ltd | Real estate | 2025 |
| JRT Precision Engineering Ltd | Manufacturing | 2025 |
| JS Harbour Limited | Real estate | 2024 |
| JS Heat Pumps Limited | Construction | 2024 |
| JS Sports Massage Ltd | Arts & recreation | 2025 |
| Julie Lorraine Fowler Ltd | Extraterritorial | 2024 |
| Junept Limited | Information & communication | 2018 |
| Just Reliable Trading Ltd | Wholesale & retail | 2025 |
| Juventus Homes Ltd | Health & social care | 2025 |
| Jvieira Biotech Consult Ltd | Professional & scientific | 2026 |
| JVR IV Ltd | Real estate | 2025 |
| JWK Investments Ltd | Wholesale & retail | 2024 |
| JZ Property Management Limited | Real estate | 2023 |
| K & L Assets Ltd | Real estate | 2024 |
| K J Consultants Ltd | Professional & scientific | 2021 |
| K P COX Accounting Ltd | Professional & scientific | 2014 |
| K Slade HR Consulting Ltd | Administrative & support | 2025 |
| K&S Fuel Services Ltd | Wholesale & retail | 2018 |
| K-View Solutions Ltd | Professional & scientific | 2016 |
| K.Mac Carpentry Ltd | Construction | 2023 |
| Kacy Investments Ltd | Real estate | 2023 |
| Kadan Kadan UK Ltd | Transport & logistics | 2017 |
| Kairospoint Holdings Ltd | Real estate | 2025 |
| Kamdara Properties Limited | Real estate | 2025 |
| Kamla Investments Limited | Real estate | 2025 |
| Kanchana Property UK Ltd | Real estate | 2025 |
| Kanchana UK Private Limited | Administrative & support | 2016 |
| Kannaki Boutique Ltd | Wholesale & retail | 2026 |
| Kaopa (UK) Limited | Transport & logistics | 1997 |
| Kapp Consulting Ltd | Information & communication | 2017 |
| Karajeh Investments Ltd | Real estate | 2025 |
| Kargo Carpentry Ltd | Manufacturing | 2024 |
| Karma to Karma Investments Ltd | Real estate | 2025 |
| Kasia Polish Market Ltd | Wholesale & retail | 2024 |
| Kasia Polish Shop Ltd | Wholesale & retail | 2015 |