| Jarvi Technologies Limited | Information & communication | 2018 |
| Jarvis Media Ltd | Health & social care | 2017 |
| Jarvis Rail Limited | Information & communication | 1994 |
| JAS Contruction Services Ltd | Construction | 2016 |
| JAS Management Ltd | Households | 2019 |
| JAS Motortrade Ltd | Wholesale & retail | 2024 |
| JAS Technology (UK) Limited | Professional & scientific | 2010 |
| Jasan Properties Limited | Real estate | 2025 |
| Jascarm International Limited | Administrative & support | 2024 |
| Jasdal Properties Limited | Real estate | 2023 |
| Jasina Transport Limited | Transport & logistics | 2009 |
| Jasis Properties Ltd | Real estate | 2022 |
| Jaskd Limited | Transport & logistics | 2020 |
| Jaskirat SINGH1 Ltd | Construction | 2025 |
| Jasmin Allen Design Ltd | Professional & scientific | 2025 |
| Jasmin Catering Ltd | Hospitality | 2019 |
| Jasmin Thai Ltd | Hospitality | 2024 |
| Jasmine Island Limited | Information & communication | 2021 |
| Jasmira Jewelry Ltd | Wholesale & retail | 2025 |
| Jason Huang Ltd | Wholesale & retail | 2025 |
| Jason Ramtahal Limited | Health & social care | 2014 |
| Jason Reed Limited | Professional & scientific | 2022 |
| Jasper (Llandaff) Management Company Limited | Households | 1981 |
| Jass Estates Limited | Real estate | 2017 |
| Jastoo Group London Limited | Real estate | 2019 |
| Jaswinder SINGH1 Ltd | Construction | 2025 |
| Jaszacki Property Group Ltd | Real estate | 2018 |
| Jata Accountants Limited | Professional & scientific | 2022 |
| Jata Investments Limited | Financial services | 2024 |
| Jathwa Ltd | Professional & scientific | 2026 |
| Jav's Ltd | Other services | 2025 |
| Java AWA Ltd | Wholesale & retail | 2025 |
| Javed Mart Ltd | Wholesale & retail | 2026 |
| Javelin Group Holdings Limited | Professional & scientific | 2019 |
| Javire Ltd | Wholesale & retail | 2025 |
| Jawad Limited | Wholesale & retail | 2026 |
| Jawad Riaz Textile Ltd | Wholesale & retail | 2025 |
| Jawhara Group Ltd | Professional & scientific | 2023 |
| Jawsram Limited | Health & social care | 2019 |
| Jaxion Ltd | Manufacturing | 2025 |
| JAY Baulch Motion Design Ltd | Information & communication | 2025 |
| JAY Enterprises Ltd | Administrative & support | 2019 |
| JAY Gildea Limited | Information & communication | 2018 |
| JAY Services Management Ltd | Hospitality | 2019 |
| Jay's Fxholdings & Account Managements Ltd | Financial services | 2025 |
| Jay-Jay Clean UP Limited | Administrative & support | 2025 |
| Jay-Krishna Ltd | Wholesale & retail | 2010 |
| Jayaro Automobiles Limited | Wholesale & retail | 2024 |
| Jaybaba Limited | Wholesale & retail | 2021 |
| Jaybeats Limited | Arts & recreation | 2021 |
| Jaycliff Limited | Real estate | 2005 |
| Jaycombe Limited | Construction | 2018 |
| Jaycourt Limited | Construction | 2020 |
| Jaydab Ltd | Professional & scientific | 2025 |
| Jayden FOX Ltd | Wholesale & retail | 2019 |
| Jaydenleo Food Ltd | Wholesale & retail | 2023 |
| Jaydun Williams Limited | Wholesale & retail | 2025 |
| Jayflex Ltd | Wholesale & retail | 2020 |
| Jayimpact Solutions Ltd | Real estate | 2021 |
| Jaykay Medical Solutions Ltd | Wholesale & retail | 2013 |
| Jaymo Solutions Limited | Administrative & support | 2015 |
| Jayr Limited | Real estate | 2009 |
| Jays Group Ltd | Hospitality | 2024 |
| Jays Painting Limited | Construction | 2025 |
| Jays Traction Ltd | Transport & logistics | 2023 |
| Jaystreet Limited | Real estate | 1973 |
| Jayveer Estates Ltd | Real estate | 2024 |
| Jaz.Cam Ltd | Professional & scientific | 2024 |
| Jazen Industry Co., Ltd. | Manufacturing | 2023 |
| Jazmelo Solutions Ltd | Administrative & support | 2021 |
| Jazz at Penylan Festival CIC | Arts & recreation | 2026 |
| Jazz Computers Limited | Information & communication | 1988 |
| Jazz Trading Limited | Wholesale & retail | 2024 |
| Jazzera Holdings Ltd | Real estate | 2017 |
| JB & KM Structural Consultants and Designers Ltd | Professional & scientific | 2024 |
| JB Bridal Limited | Wholesale & retail | 2015 |
| JB Build&Fix Ltd | Manufacturing | 2026 |
| JB Choice International Trading Ltd | Wholesale & retail | 2023 |
| JB Construction (Cardiff) Limited | Construction | 2014 |
| JB Engineering Services (Essex) Ltd | Professional & scientific | 2014 |
| JB Holdings (Midlands) Limited | Hospitality | 2019 |
| JB Projects Ltd | Transport & logistics | 2021 |
| JB Property Letting and Investment Ltd | Real estate | 2022 |
| JB Railway Limited | Manufacturing | 2016 |
| JB Tutors Online School Ltd | Education | 2024 |
| JB7 Promotions Ltd | Arts & recreation | 2021 |
| JB7 Properties Ltd | Hospitality | 2023 |
| JBA Home Ltd | Wholesale & retail | 2024 |
| Jbah Trading Ltd | Wholesale & retail | 2025 |
| JBC Europe Ltd | Manufacturing | 2018 |
| Jbcds Services Ltd | Professional & scientific | 2025 |
| Jbcosmetic Aesthetics Limited | Health & social care | 2022 |
| JBE Actuary Limited | Financial services | 2021 |
| JBE Scotland Ltd | Administrative & support | 2013 |
| JBG Group Limited | Other services | 2015 |
| JBK Property Holdings Ltd | Real estate | 2025 |
| Jbla Limited | Wholesale & retail | 2024 |
| JBM Products Limited | Construction | 2020 |
| JBR Commercial Property Group Limited | Real estate | 2018 |
| Jbrd Ventures Limited | Arts & recreation | 2025 |