| Jarek-Pol Ltd | Transport & logistics | 2013 |
| Jark 101 Limited | Real estate | 2022 |
| Jark 102 Limited | Other services | 2022 |
| Jark 103 Limited | Real estate | 2022 |
| Jark 104 Limited | Real estate | 2022 |
| Jark 105 Limited | Other services | 2023 |
| Jark 106 Limited | Other services | 2024 |
| Jark 5 Limited | Real estate | 2020 |
| Jark Lettings UK Limited | Real estate | 2019 |
| Jark Portfolio Management Limited | Households | 2024 |
| Jark Security Trustee Limited | Administrative & support | 2018 |
| JARK-2 Limited | Real estate | 2017 |
| JARK-4 Ltd | Real estate | 2020 |
| JARK-8 Ltd | Real estate | 2019 |
| JAS Dental Services Limited | Health & social care | 2024 |
| Jasam Technology Limited | Professional & scientific | 2007 |
| Jasec Limited | Information & communication | 2016 |
| Jasher Design Ltd | Professional & scientific | 2022 |
| Jasi Group Ltd | Administrative & support | 2026 |
| Jasmingreen Ltd | Professional & scientific | 2024 |
| Jason Peters Ltd | Transport & logistics | 2023 |
| Jasper Engineering Limited | Administrative & support | 2013 |
| Jasper Harrison Limited | Administrative & support | 2007 |
| Javaid Medical Limited | Health & social care | 2016 |
| Javelin Technology Limited | Information & communication | 2012 |
| JAX Eco Heat Ltd | Construction | 2025 |
| JAX Engineering Ltd | Professional & scientific | 2024 |
| JAY Abeyratne Limited | Information & communication | 2025 |
| JAY Charis Limited | Information & communication | 2012 |
| Jayla Solutions Limited | Other services | 2017 |
| Jayne Bray Limited | Extraterritorial | 2023 |
| Jazz Quality Concepts Ltd | Administrative & support | 2009 |
| Jazzlocums Ltd | Wholesale & retail | 2022 |
| JB & JB Construction Ltd | Construction | 2021 |
| JB and ZB Ltd | Construction | 2019 |
| JB Content Design Limited | Information & communication | 2019 |
| JB Direction and Design Ltd | Professional & scientific | 2019 |
| JB Hughes Ltd | Real estate | 2020 |
| JB Price Distribution Limited | Transport & logistics | 2024 |
| JB Safety Solutions Limited | Other services | 2019 |
| JB Steel Limited | Administrative & support | 2014 |
| JB Transformation & Change Ltd | Professional & scientific | 2024 |
| JB1GOALKEEPING Ltd | Education | 2021 |
| Jbel Pharma Consulting Limited | Administrative & support | 2025 |
| Jbjv Ltd | Wholesale & retail | 2009 |
| Jblc Reserve Ltd | Financial services | 2026 |
| JBM Podiatry Limited | Administrative & support | 2016 |
| JBS Consulting Limited | Administrative & support | 2008 |
| JBY Consulting Limited | Administrative & support | 2021 |
| JC Business Acounting Ltd | Professional & scientific | 2019 |
| JC Cyber Security Solutions Ltd | Information & communication | 2025 |
| JC Developments Cheshire Ltd | Real estate | 2023 |
| JC Electrical Engineering Limited | Professional & scientific | 2016 |
| JC Interior Solutions Ltd | Construction | 2021 |
| JC Process Engineering Ltd | Professional & scientific | 2025 |
| JC Wronskian Limited | Information & communication | 2014 |
| Jc's Technologies Ltd | Information & communication | 2024 |
| Jcass Consultancy Limited | Professional & scientific | 2023 |
| JCB Design Services Limited | Administrative & support | 2012 |
| JCE Engineering Limited | Administrative & support | 2013 |
| JCG Global Limited | Wholesale & retail | 2023 |
| JCH Golf Ltd | Arts & recreation | 2018 |
| JCK Catering Ltd | Hospitality | 2021 |
| JCL Mechanical Engineering & Fitting Ltd | Administrative & support | 2025 |
| JCM Groundworks & Landscaping Ltd | Administrative & support | 2022 |
| JCP QA Ltd | Administrative & support | 2025 |
| Jcrowe Engineering Ltd | Professional & scientific | 2025 |
| JCS Civil & Construction Limited | Administrative & support | 2025 |
| JCS Travel Limited | Administrative & support | 2018 |
| Jcsi ADV Ltd | Professional & scientific | 2026 |
| JCW Consultancy Ltd | Professional & scientific | 2025 |
| JCW Quality Management Ltd | Administrative & support | 2025 |
| JD Change Solutions Limited | Information & communication | 2023 |
| JD Electrical Cheshire Ltd | Construction | 2024 |
| JD Events NW Ltd | Other services | 2021 |
| JD Hall Limited | Administrative & support | 2015 |
| JD86 Engineering Limited | Administrative & support | 2015 |
| Jdak Consulting Ltd | Administrative & support | 2025 |
| Jdam Associates Limited | Professional & scientific | 2015 |
| Jdar Properties Ltd | Real estate | 2020 |
| JDF Engineering Solutions Limited | Administrative & support | 2014 |
| JDG Media Ltd | Information & communication | 2011 |
| JDH Stats Limited | Information & communication | 2012 |
| JDI IT Services Limited | Information & communication | 2012 |
| JDM Heart Care Limited | Administrative & support | 2015 |
| JDN Group Limited | Financial services | 2022 |
| JDN Property Group Ltd | Real estate | 2024 |
| JDP & Partners Limited | Administrative & support | 2022 |
| Jdprevit Limited | Administrative & support | 2024 |
| JDW Civils Ltd | Administrative & support | 2026 |
| JDW Services Limited | Other services | 2004 |
| JE & SR Clark Limited | Health & social care | 2015 |
| JE Health Ltd | Health & social care | 2022 |
| JE Partners Limited | Real estate | 2021 |
| Jean-Paul Software Ltd | Professional & scientific | 2020 |
| Ject Ltd | Wholesale & retail | 2025 |
| Jedc Football Performance Ltd | Education | 2024 |
| Jedr Property Management Ltd | Real estate | 2023 |
| Jefferson Global Security Limited | Administrative & support | 2011 |
| JEH 70 Engineering Limited | Professional & scientific | 2016 |