| JNS Building Services Ltd | Construction | 2022 |
| JNS Ceramics Ltd | Construction | 2017 |
| JNS Electrical Services Ltd | Construction | 2016 |
| Jo's Cakes Limited | Hospitality | 2014 |
| Jodie Glover Tattoos Ltd | Arts & recreation | 2023 |
| Jodup Medics Consultancy Limited | Health & social care | 2012 |
| JOE Global Services Limited | Health & social care | 2018 |
| Johanson Ltd | Construction | 2019 |
| John & MAY Ltd | Construction | 2023 |
| John London Limited | Construction | 2025 |
| John Removals Ltd | Transport & logistics | 2025 |
| Jojomark Limited | Construction | 2015 |
| Jojovizi Ltd | Professional & scientific | 2026 |
| Jola Services Ltd | Extraterritorial | 2011 |
| JON Jarvis Contractor Ltd | Arts & recreation | 2013 |
| Jonas Electrical Services Limited | Construction | 2018 |
| Jonson & Allington Estates Limited | Real estate | 2017 |
| Jordan Jayne Property Ltd | Real estate | 2022 |
| Jordan Park Ltd | Information & communication | 2019 |
| Jordan T Noyes Holdings Limited | Financial services | 2023 |
| Josadel Ltd | Information & communication | 2025 |
| Josetom Ltd | Wholesale & retail | 2023 |
| Josh Williams Tattoo Ltd | Arts & recreation | 2021 |
| Jouch Consultancy Ltd | Construction | 2018 |
| Jovada Express Ltd | Transport & logistics | 2011 |
| Jovika Ltd | Manufacturing | 2019 |
| Joyceilawa Ltd | Health & social care | 2021 |
| Joyforge Ltd | Manufacturing | 2025 |
| Joynab Spice Limited | Hospitality | 2026 |
| Jozga Ltd | Construction | 2022 |
| JP Carpentry Ltd | Construction | 2017 |
| JP Fire Solutions Ltd | Construction | 2024 |
| JPC Services (South East) Ltd | Construction | 2023 |
| JPR Roofing Contractors Ltd | Construction | 2024 |
| JR Bird Management Ltd | Administrative & support | 2022 |
| JR Commercial Services Ltd | Professional & scientific | 2016 |
| JR Nightingale Ltd | Professional & scientific | 2014 |
| JRD Agency Ltd | Wholesale & retail | 2021 |
| JRS Family Holdings Limited | Financial services | 2025 |
| JS Lets Ltd | Real estate | 2022 |
| JS Miller Services Ltd | Other services | 2018 |
| JS Pharma London Ltd | Health & social care | 2023 |
| JS Plumbing Limited | Construction | 2025 |
| JS Plus Ltd | Wholesale & retail | 2025 |
| JS Psychology Ltd | Health & social care | 2023 |
| JSB Groundworks Limited | Construction | 2014 |
| JSD Civils Management Limited | Construction | 2023 |
| JSM Digital Marketing Ltd | Professional & scientific | 2025 |
| JSM Flooring Ltd | Construction | 2025 |
| JSM Property Ltd | Real estate | 2022 |
| JSM Telecom Ltd | Information & communication | 2021 |
| JT Goldsack Carpentry Ltd | Construction | 2019 |
| JT Jawk Limited | Real estate | 2023 |
| JTD Trans Services Ltd | Transport & logistics | 2019 |
| JTS Devine Ltd | Administrative & support | 2019 |
| Jubileebay Limited | Other services | 1995 |
| Juels Services Limited | Real estate | 2025 |
| Julia Gaughan Education Ltd | Education | 2023 |
| Julian Ford Consulting Ltd | Transport & logistics | 2013 |
| Junkmove Limited | Water & waste | 2024 |
| Jusball Health & Education Community Interest Company | Education | 2021 |
| Jusball Media Ltd | Arts & recreation | 2020 |
| Just ASK Engineering Ltd | Professional & scientific | 2018 |
| Justbills Limited | Wholesale & retail | 2026 |
| Justin Interior Ltd | Construction | 2023 |
| Juststarted.Co Ltd | Information & communication | 2025 |
| Juwe INT. Ltd | Administrative & support | 2018 |
| JV Windsor(Property) Ltd | Real estate | 2017 |
| JV888MD Limited | Hospitality | 2019 |
| JW & Co Maintenance Ltd | Construction | 2022 |
| JW & LJ Brasier Limited | Professional & scientific | 2010 |
| JW Holdco Ltd | Professional & scientific | 2023 |
| JW Properties Ltd | Real estate | 2023 |
| JW Retail Consultants Limited | Wholesale & retail | 2023 |
| JW Services Ltd | Construction | 2024 |
| JWL Electrical Contracting Ltd | Construction | 2026 |
| JWN & Sons Ltd | Construction | 2018 |
| JWT Media Ltd | Information & communication | 2025 |
| JYO Energy Limited | Manufacturing | 2015 |
| K & M Food Suppliers Ltd | Wholesale & retail | 2021 |
| K a Bicknell Ltd | Construction | 2024 |
| K and K Pubs Ltd | Hospitality | 2023 |
| K D C Groundworks Limited | Construction | 2022 |
| K Howard Plastering Limited | Construction | 2015 |
| K K B Plant Services Limited | Construction | 2010 |
| K K B Remediation Limited | Water & waste | 2010 |
| K R Tech (South East) Ltd | Wholesale & retail | 2025 |
| K S Law Limited | Professional & scientific | 2004 |
| K&Co Property Ltd | Real estate | 2025 |
| K&K House Limited | Wholesale & retail | 2017 |
| K&N Property Group Ltd | Real estate | 2024 |
| K.Axis Ltd | Real estate | 2026 |
| K.D.B.M. Limited | Construction | 2019 |
| K.SADLER2 Ltd | Transport & logistics | 2018 |
| Kaagarootv Ltd | Extraterritorial | 2025 |
| Kabash Holdings Ltd | Real estate | 2019 |
| KAL Client Services Ltd | Administrative & support | 2020 |
| Kaleidoscope Properties Ltd | Real estate | 2024 |
| Kalez Medical Ltd | Health & social care | 2021 |
| Kalikas Armour Ltd | Manufacturing | 2023 |