| Jacksn Limited | Wholesale & retail | 2025 |
| Jackson & Board Limited | Professional & scientific | 2024 |
| Jackson B Ltd | Construction | 2020 |
| Jackson Close Limited | Information & communication | 2009 |
| Jackson Court (Parklands) Management Company Limited | Households | 2002 |
| Jackson Handling Limited | Wholesale & retail | 2010 |
| Jackson Retail, Staffordshire Ltd | Wholesale & retail | 2021 |
| Jackson Services Ltd | Wholesale & retail | 2021 |
| Jacksonrans Ltd | Wholesale & retail | 2024 |
| Jacksons Capital Ltd | Financial services | 2023 |
| Jacksonwellrecruitment Limited | Administrative & support | 2024 |
| Jacky JY Co., Ltd | Information & communication | 2021 |
| Jack’S Flight Club (UK) Limited | Information & communication | 2021 |
| Jacob Junior Ltd | Other services | 2017 |
| Jacob LEE London Limited | Wholesale & retail | 2012 |
| Jacob Legal Support Services Limited | Wholesale & retail | 2016 |
| Jacob's Surveys Limited | Professional & scientific | 2016 |
| Jacobs & Field Inc. Ltd | Hospitality | 2013 |
| Jacobs and Co (Cardiff) Ltd | Hospitality | 2025 |
| Jacobs and Harris Limited | Financial services | 2012 |
| Jacques Interior Finishes Ltd | Construction | 2020 |
| JAD European Ltd | Transport & logistics | 2022 |
| Jadach Estates Ltd | Real estate | 2022 |
| Jadason Limited | Construction | 2017 |
| Jade 49 Ltd | Real estate | 2025 |
| Jade Business Services Ltd | Construction | 2018 |
| Jade Fisher Ltd | Wholesale & retail | 2017 |
| Jade Freight Co., Ltd | Professional & scientific | 2013 |
| Jade Tizzard Limited | Wholesale & retail | 2025 |
| JADE2018 Healthcare Ltd | Health & social care | 2018 |
| Jadebloom Limited | Wholesale & retail | 2025 |
| Jaded Construction Ltd | Construction | 2026 |
| Jadeite Marketing Limited | Professional & scientific | 2023 |
| Jadesbargains Limited | Wholesale & retail | 2026 |
| Jadewynn Limited | Wholesale & retail | 2025 |
| Jadon Trading BV Ltd | Wholesale & retail | 2025 |
| Jads Property Ltd | Real estate | 2019 |
| Jady Consultants Ltd | Information & communication | 2014 |
| Jael Cleaning Services Ltd | Administrative & support | 2025 |
| Jael.Shop Ltd | Wholesale & retail | 2024 |
| Jaey Snow Ltd | Professional & scientific | 2018 |
| JAF (Yeovil) Limited | Construction | 2006 |
| JAF Market Ltd | Wholesale & retail | 2024 |
| JAF Products (UK) Limited | Agriculture & fishing | 2009 |
| Jafa Developments Limited | Households | 2025 |
| Jafar Dental Ltd | Health & social care | 2025 |
| Jafco Madinah Investment Limited | Real estate | 2022 |
| Jaffi Properties Limited | Real estate | 2023 |
| Jafir Global Ltd | Wholesale & retail | 2025 |
| Jafs Leasing Ltd | Real estate | 2026 |
| Jafs Lettings & Sales Ltd | Real estate | 2021 |
| Jafs Properties Ltd | Real estate | 2020 |
| Jafs Transports Ltd | Transport & logistics | 2018 |
| JAG Capital Ltd | Financial services | 2019 |
| JAG Catering Equipment Limited | Administrative & support | 2022 |
| JAG Contracting Ltd | Professional & scientific | 2018 |
| JAG Sport Horses Ltd | Agriculture & fishing | 2021 |
| Jagabee Ltd | Information & communication | 2024 |
| Jagami Properties Ltd | Real estate | 2021 |
| Jagatheeswaram Events Ltd | Hospitality | 2019 |
| Jagdeep SINGH1 Ltd | Construction | 2022 |
| Jaggerd Limited | Wholesale & retail | 2021 |
| Jagjeet SINGH1 Ltd | Construction | 2022 |
| Jagodzinska Project Management Ltd | Information & communication | 2023 |
| Jagroom Ltd | Wholesale & retail | 2026 |
| Jagroop SINGH1 Ltd | Construction | 2025 |
| Jags Information Systems Ltd | Information & communication | 2008 |
| Jaguar Leather Company Limited | Wholesale & retail | 2025 |
| Jaguar Security Solutions Ltd | Administrative & support | 2018 |
| Jaguarfm Limited | Administrative & support | 2018 |
| JAH Beauty Limited | Wholesale & retail | 2020 |
| JAH Inc Ltd | Professional & scientific | 1997 |
| JAH Payroll Consultants Limited | Professional & scientific | 2013 |
| Jahan Sushi Bite Ltd | Hospitality | 2019 |
| Jahmastic Core Limited | Construction | 2026 |
| Jahtek Ltd | Real estate | 2018 |
| JAI Guru JI Ltd | Information & communication | 2015 |
| JAI Smith Ltd | Construction | 2025 |
| JAI Trading Inc Ltd | Information & communication | 2024 |
| JAI YEN LLP | | 2021 |
| Jaibon Limited | Real estate | 2006 |
| Jaime Limited | Wholesale & retail | 2025 |
| Jaiprabaa Limited | Health & social care | 2015 |
| Jairaj ERA Ltd | Manufacturing | 2025 |
| Jaisal Properties Ltd | Real estate | 2022 |
| Jaison's Management Co. Ltd | Health & social care | 2019 |
| Jaivine | Professional & scientific | 2025 |
| Jaiy Motion Limited | Arts & recreation | 2019 |
| JAJ (U.K.) General Trading Ltd | Professional & scientific | 2019 |
| Jake Tanguay Ltd | Health & social care | 2016 |
| Jake Walsh Roofing Limited | Construction | 2019 |
| Jaki & SON Ltd | Professional & scientific | 2014 |
| Jakkob Limited | Arts & recreation | 2024 |
| Jakob Vonge Nielsen Limited | Professional & scientific | 2018 |
| Jakpa Logistics and Travels Limited | Transport & logistics | 2024 |
| Jalapeno's Pizza Ltd | Hospitality | 2019 |
| Jalematt Cooks Limited | Hospitality | 2026 |
| Jalexkam Property Investment Ltd | Construction | 2019 |
| Jalmics International Ltd | Professional & scientific | 2019 |
| Jalo and Stitch Ltd | Wholesale & retail | 2025 |