| JFR Business Services Ltd | Professional & scientific | 2016 |
| JG Building & Maintenance Limited | Construction | 2015 |
| JG Cleaners Ltd | Administrative & support | 2019 |
| JG Fusion Ltd | Information & communication | 2025 |
| JGK Butchers & Delicatessen Ltd | Manufacturing | 2024 |
| JGS Hamstead Consultancy Limited | Professional & scientific | 2014 |
| JGS Property Ltd | Construction | 2016 |
| JH Brickwork (Swindon) Limited | Construction | 2018 |
| JH Miller Consulting Ltd | Information & communication | 2023 |
| JHA Holidays Ltd | Real estate | 2022 |
| JHJ Facilities Support Limited | Real estate | 2003 |
| JHS Homes Limited | Households | 2020 |
| JHT Partnership LLP | | 2017 |
| Jibril Transport Ltd | Transport & logistics | 2022 |
| Jicsaw (Cricklade) Ltd | Hospitality | 2018 |
| Jigsaw Arts Crouch END LLP | | 2026 |
| Jigsaw Arts Mitcham, Sutton and Wimbledon LLP | | 2024 |
| Jigsaw Brand Consultancy Limited | Wholesale & retail | 2020 |
| Jigsaw Chelmsford and Brentwood LLP | | 2025 |
| Jigsaw Performing Arts Cardiff & Penarth LLP | | 2025 |
| Jigsaw Performing Arts Hemel Hempstead LLP | | 2026 |
| Jigsaw Performing Arts Watford Bushey LLP | | 2024 |
| Jigstudy Ltd | Manufacturing | 2021 |
| Jiina Ltd | Transport & logistics | 2024 |
| JIM Will Plumbing and Heating Limited | Construction | 2017 |
| Jimmy RAE Drylining Ltd | Construction | 2023 |
| Jimmy's Kebab Ltd | Hospitality | 2025 |
| Jimoddity Limited | Wholesale & retail | 2021 |
| Jiyu Consulting Ltd | Administrative & support | 2011 |
| Jiyu People Ltd | Administrative & support | 2025 |
| JJ Building & Renovation Ltd | Construction | 2012 |
| JJ Earnshaw Medicolegal Limited | Health & social care | 2015 |
| JJ Medical Services Limited | Health & social care | 2018 |
| JJ Property and Developments Limited | Real estate | 2016 |
| JJ Solutions Swindon Ltd | Administrative & support | 2025 |
| JJ Tech Services Ltd | Information & communication | 2022 |
| Jj's Plumbing & Heating Limited | Construction | 2017 |
| Jjbba Nottingham LLP | | 2010 |
| JJF Consulting Ltd | Information & communication | 2026 |
| JJL International Ltd | Wholesale & retail | 2025 |
| Jjzielina Ltd | Transport & logistics | 2016 |
| JK Bespoke Tiling Solutions Ltd | Construction | 2024 |
| JK Commercial Practitioners Ltd | Administrative & support | 2025 |
| JK Global Trans Ltd | Transport & logistics | 2025 |
| JK Haulage Solutions Ltd | Transport & logistics | 2025 |
| JK002 Ltd | Financial services | 2019 |
| JKP BIZ Services Ltd | Public administration | 2022 |
| JKV Properties Ltd | Real estate | 2019 |
| JKV Stores Ltd | Wholesale & retail | 2013 |
| JL Mindset Performance Ltd | Other services | 2004 |
| JL Nails Ltd | Other services | 2024 |
| JL People Resolutions Ltd | Administrative & support | 2023 |
| JL Services 247 Ltd | Wholesale & retail | 2025 |
| Jlam Services Limited | Professional & scientific | 2024 |
| Jlbrickwork SW Ltd | Construction | 2025 |
| Jlenn Ltd | Wholesale & retail | 2025 |
| JLH Showjumping Ltd | Agriculture & fishing | 2025 |
| Jljc Properties Limited | Real estate | 2024 |
| Jlma Colwyn Bay LLP | | 2018 |
| Jlmc Associates Ltd | Construction | 2026 |
| JLP Consultancy Ltd | Information & communication | 2018 |
| JLR 2 Ltd | Wholesale & retail | 2025 |
| JLR Park Ltd | Wholesale & retail | 2022 |
| JM Audio Productions Limited | Arts & recreation | 2023 |
| JM Concept Ltd | Professional & scientific | 2024 |
| JM Feltham Sushi Limited | Hospitality | 2025 |
| JM Francisco Ltd | Wholesale & retail | 2023 |
| JM Highway Consultancy Ltd | Construction | 2023 |
| JM Oneclinic Limited | Professional & scientific | 2023 |
| JM Reading Sushi Ltd | Hospitality | 2024 |
| JM Renovations Ltd | Construction | 2019 |
| JM Square Ltd | Education | 2024 |
| JMC Carpentry Ltd | Manufacturing | 2023 |
| JMC Commercial Hub Limited | Real estate | 2024 |
| JMC Construction Limited | Construction | 2013 |
| JMC Property Solutions Limited | Real estate | 2018 |
| JMC2 Limited | Information & communication | 2022 |
| Jmcivil Construction Services Limited | Construction | 2017 |
| JMD Universe Limited | Professional & scientific | 2019 |
| Jmedia Global Ltd | Information & communication | 2025 |
| JMG UK Group Limited | Administrative & support | 2024 |
| Jmjm Properties Ltd | Real estate | 2022 |
| JMR19 Ltd | Hospitality | 2019 |
| JMS Telecoms Ltd | Information & communication | 2018 |
| JMV Consulting Ltd | Information & communication | 2016 |
| JN566 Ltd | Hospitality | 2024 |
| JNB Ventures Limited | Real estate | 2024 |
| JNM Claim Specialists Ltd | Professional & scientific | 2025 |
| JNM Supply Chain Ltd | Professional & scientific | 2017 |
| JO Rodwell Limited | Professional & scientific | 2007 |
| Jo&Ma Limited | Construction | 2019 |
| JO37 Limited | Wholesale & retail | 2014 |
| Joanna Cesarz Consultancy Limited | Wholesale & retail | 2017 |
| Joanna Cesarz Limited | Arts & recreation | 2018 |
| Joanna DE Waal Ltd | Other services | 2021 |
| JOB Logistics Limited | Transport & logistics | 2012 |
| Jobestle Limited | Health & social care | 2018 |
| Jobfast Ltd | Information & communication | 2026 |
| Jodie Amelia Hairdressing Limited | Other services | 2018 |
| Joe's Fine Foods Ltd | Hospitality | 2023 |