| JAC Construct Services Ltd | Construction | 2022 |
| Jack Charlton Ltd | Wholesale & retail | 2024 |
| Jack Mully Ltd | Information & communication | 2021 |
| Jack Nails Limited | Other services | 2024 |
| Jackenn Limited | Information & communication | 2013 |
| Jackpup Limited | Real estate | 2024 |
| Jacksonn Ltd | Professional & scientific | 2026 |
| Jackston Limited | Real estate | 1997 |
| Jacob Tech Limited | Information & communication | 2026 |
| Jacobauto Limited | Wholesale & retail | 2025 |
| Jacobs of Harrow Ltd | Wholesale & retail | 2008 |
| Jacobs Roofing Services Ltd | Construction | 2023 |
| Jacomah Limited | Real estate | 2018 |
| Jacqueline Culleton Limited | Other services | 2017 |
| Jacqueline Parker Ltd | Other services | 2012 |
| Jade Capital Investments Limited | Real estate | 2019 |
| Jade Global UK Ltd | Information & communication | 2016 |
| Jadeanne’S Studio Ltd | Other services | 2023 |
| Jadon Group Ltd | Wholesale & retail | 2019 |
| Jaduby Ltd | Information & communication | 2023 |
| Jaenak Limited | Administrative & support | 2014 |
| Jafare Consulting Solutions Ltd | Professional & scientific | 2025 |
| Jaffna Solutions Limited | Information & communication | 2015 |
| Jaffoo Properties Ltd | Real estate | 2024 |
| Jaffoo Solutions Ltd | Information & communication | 2017 |
| Jaffsons Mercantile Company Limited | Construction | 1975 |
| Jafim Holdings Ltd | Real estate | 2022 |
| Jagdamb Sports and Equipment Ltd | Wholesale & retail | 2026 |
| Jagdish Patel & Sons Limited | Other services | 2009 |
| Jagger Investments Ltd | Real estate | 2013 |
| Jaglan Dwell Limited | Real estate | 2023 |
| Jagrit Shah Limited | Health & social care | 2019 |
| Jagu Tours & Travels Ltd | Administrative & support | 2026 |
| Jaguar Fighting Championship Ltd | Arts & recreation | 2023 |
| Jaguar Wholesalers Limited | Hospitality | 2023 |
| Jahaj 2 Ltd | Real estate | 2020 |
| Jahaj 3 Ltd | Real estate | 2020 |
| JAI & EMM Ltd | Wholesale & retail | 2021 |
| JAI Amskhil Limited | Professional & scientific | 2014 |
| JAI Mahadev Limited | Professional & scientific | 2016 |
| JAI Shah Photography Limited | Other services | 2012 |
| JAI Thurka Limited | Hospitality | 2016 |
| Jaika Import Ltd | Wholesale & retail | 2024 |
| Jaime Properties Limited | Real estate | 2018 |
| Jaime Valtierra Art Service Ltd | Arts & recreation | 2018 |
| Jaimil Creation Ltd | Wholesale & retail | 2013 |
| Jaimin Property Management LLP | | 2013 |
| Jainex International Limited | Financial services | 1973 |
| Jains Consulting Ltd | Real estate | 2013 |
| Jaipur LAB Jewellery Ltd | Wholesale & retail | 2025 |
| JAJ Pharma Limited | Professional & scientific | 2016 |
| JAK Live Ltd | Arts & recreation | 2026 |
| JAK99 Ltd | Extraterritorial | 2023 |
| Jakeman Roofing Ltd | Construction | 2022 |
| Jakharia Properties Limited | Real estate | 2011 |
| Jakobz Editing Ltd | Professional & scientific | 2024 |
| Jakobz Media Ltd | Information & communication | 2023 |
| Jaladeep Limited | Wholesale & retail | 2012 |
| Jalakrupa (Beauty and Spa) Ltd | Other services | 2012 |
| Jalakrupa (Investment Properties) Ltd | Real estate | 2021 |
| Jalalzai Housing Limited | Hospitality | 2026 |
| Jalaram Grocery Ltd | Wholesale & retail | 2025 |
| Jalaram Holdings Ltd | Real estate | 2018 |
| Jalaram Property Ltd | Other services | 2024 |
| Jalaram Rent to Buy Ltd | Wholesale & retail | 2024 |
| Jalif Investments Limited | Financial services | 2018 |
| Jallas Property 1 Limited | Real estate | 2007 |
| Jallas Property 2 Limited | Real estate | 2020 |
| Jalloway Limited | Information & communication | 2009 |
| Jalsa Paan Limited | Wholesale & retail | 2019 |
| JAM Brothers Limited | Construction | 2021 |
| JAM Family Investments Limited | Real estate | 2018 |
| JAM Holdings (Hatch END) Limited | Administrative & support | 2021 |
| JAM Islamic Inspirations Ltd | Professional & scientific | 2025 |
| JAM Property Developments Limited | Real estate | 2025 |
| JAM Pubs and Restaurants Limited | Hospitality | 2025 |
| Jamal Electrical Services Ltd | Construction | 2021 |
| Jamal Hashi Limited | Professional & scientific | 2022 |
| Jamame Ltd | Hospitality | 2023 |
| Jamd Properties Limited | Real estate | 2017 |
| Jameel Properties Limited | Real estate | 2026 |
| James Alexander Design Limited | Professional & scientific | 2022 |
| James and Cranwell Limited | Administrative & support | 2016 |
| James Bradshaw Consulting Ltd | Professional & scientific | 2024 |
| James Byrne Electrical Limited | Construction | 2022 |
| James Charles Engineering Ltd | Professional & scientific | 2018 |
| James Funeral Service Ltd | Other services | 2011 |
| James Gregory Ltd | Wholesale & retail | 2020 |
| James Lindsay Associates Limited | Professional & scientific | 2008 |
| James Meakin Photography Limited | Professional & scientific | 2013 |
| James Nicholson Design Limited | Professional & scientific | 2022 |
| James Owen Investments Limited | Real estate | 2020 |
| James Russell Limited | Wholesale & retail | 2003 |
| Jameson's Bar Limited | Hospitality | 2004 |
| Jamie Rail Ltd | Construction | 2024 |
| Jamk Limited | Real estate | 1960 |
| Jamna Varsani Ltd | Real estate | 2019 |
| Jamoh Properties Limited | Real estate | 2024 |
| Jamon 77 Ltd | Hospitality | 2013 |
| Jamosan Limited | Professional & scientific | 2025 |