| Jain Holmes Ltd | Health & social care | 2016 |
| Jaishiva Limited | Real estate | 2024 |
| JAK Telecom Ltd | Wholesale & retail | 2016 |
| Jalali Consultants Ltd | Wholesale & retail | 2018 |
| Jalip Enterprises Ltd | Wholesale & retail | 2024 |
| Jalipex Ltd | Wholesale & retail | 2025 |
| JAM Packed Preserves Limited | Manufacturing | 2020 |
| James Allen Corp Ltd | Professional & scientific | 2006 |
| James Bailey Property Limited | Real estate | 2021 |
| James Brown Refurbishments Limited | Construction | 2017 |
| James Dean Developments Ltd | Construction | 2016 |
| James Mullen Limited | Construction | 2014 |
| James Path Network Ltd | Information & communication | 2018 |
| James's Properties Limited | Real estate | 2025 |
| Jamie Wilson Productions Limited | Arts & recreation | 2008 |
| Jamie Wilson Theatre Limited | Arts & recreation | 2015 |
| Jamie Wood Ltd | Information & communication | 2013 |
| Jamy Business Support Limited | Professional & scientific | 2024 |
| Jana MJ Ltd | Health & social care | 2017 |
| Janash Properties Limited | Real estate | 2006 |
| Jane and Eric Property Limited | Real estate | 2016 |
| Jany&M Ltd | Construction | 2020 |
| Jara Vehicle Sales Limited | Wholesale & retail | 2023 |
| JASJOSH2 Ltd | Professional & scientific | 2015 |
| Jass Global Tech Limited | Wholesale & retail | 2025 |
| Jassiane Limited | Other services | 2003 |
| Java Health Ltd | Health & social care | 2021 |
| Javad Akhtar Management Ltd | Professional & scientific | 2022 |
| JAX Scaffolding Ltd | Construction | 2020 |
| JAY Mataji Limited | Wholesale & retail | 2020 |
| Jaybells Ltd | Real estate | 2023 |
| Jaycube Limited | Construction | 2020 |
| Jaymini Patel Ltd | Professional & scientific | 2020 |
| Jaysol Estates Ltd | Real estate | 2024 |
| Jazimus Limited | Arts & recreation | 2003 |
| Jazsoft Limited | Information & communication | 1998 |
| JB Forecourt Ltd | Real estate | 2026 |
| JB Housing Associates Limited | Professional & scientific | 2004 |
| JBA Healthcare Limited | Professional & scientific | 2015 |
| JBK Technologies Limited | Information & communication | 2014 |
| JBN Services Ltd | Education | 2025 |
| JBP Accounting Solutions Limited | Professional & scientific | 2019 |
| JBS Platforms and Rigging Ltd | Construction | 2018 |
| JC Electrical Surrey Ltd | Construction | 2024 |
| JC Holdings Group Ltd | Financial services | 2021 |
| Jcec Design Ltd | Professional & scientific | 2021 |
| JCS Accountants Limited | Professional & scientific | 2013 |
| JD Incorporated UK Ltd | Professional & scientific | 2012 |
| Jd's Football School Limited | Education | 2013 |
| Jdct Energy Consultants Ltd | Financial services | 2025 |
| Jdeepta Consultancy Services Limited | Information & communication | 2016 |
| Jdkw Solutions Ltd | Construction | 2014 |
| Jdsl Group Ltd | Construction | 2003 |
| JEB Services Ltd | Professional & scientific | 2022 |
| JED Investments and Leisure Ltd | Hospitality | 2023 |
| Jedmax London Ltd | Construction | 2025 |
| Jedmax Ltd | Construction | 2020 |
| JEE Engineering Services Limited | Professional & scientific | 2014 |
| Jeebei Ltd | Wholesale & retail | 2014 |
| Jembrs & KO. Ltd | Health & social care | 2017 |
| Jengar Residents Maintenance Association Limited | Households | 1976 |
| Jenkins Gardens Limited | Administrative & support | 2024 |
| Jennings (Chemists) Limited | Wholesale & retail | 1945 |
| Jerk N Jollof Express Ltd | Hospitality | 2025 |
| Jerryped Limited | Information & communication | 2018 |
| Jervis Small Holdings Limited | Households | 2025 |
| Jesmund Care Limited | Health & social care | 2017 |
| Jessica Delport Ltd | Real estate | 2024 |
| Jesus Dominion International | Other services | 1999 |
| Jesyem Medicare Limited | Health & social care | 1993 |
| JET Properties Solutions Ltd | Real estate | 2020 |
| Jethwa Consultancy Limited | Information & communication | 2004 |
| Jevvy Limited | Professional & scientific | 2004 |
| Jey's Surrey Properties Ltd | Real estate | 2023 |
| Jeya Ltd | Real estate | 2023 |
| Jeyam and Sons Properties Ltd | Real estate | 2024 |
| JF Accountancy Services Limited | Professional & scientific | 2019 |
| JF Advisory Services Ltd | Professional & scientific | 2015 |
| JFM Contractors Ltd | Construction | 2020 |
| JG5 Properties Limited | Real estate | 2026 |
| Jgmg Property Limited | Real estate | 2021 |
| Jhnl Ltd | Wholesale & retail | 2021 |
| Jhrn Property Management Limited | Real estate | 2022 |
| JIB Investment Limited | Real estate | 2020 |
| JIC Vista Limited | Professional & scientific | 2022 |
| Jiggers Couriers Ltd | Transport & logistics | 2021 |
| Jillorland Ltd | Other services | 2025 |
| Jinda Singh Construction Ltd | Construction | 2024 |
| Jingkun Chinese Arts CIC | Information & communication | 2025 |
| Jingkun Chinese Theatre Ltd | Wholesale & retail | 2025 |
| Jireh Cleaning & Maintenance Services Limited | Administrative & support | 2013 |
| JJ Cafe PIE Mash Ltd | Hospitality | 2019 |
| JJ DD Ltd | Hospitality | 2023 |
| JJ Mansion Ltd | Construction | 2013 |
| JJD Fibre Ltd | Administrative & support | 2024 |
| JJH Consulting Ltd | Professional & scientific | 2023 |
| JJL Real Estates Limited | Construction | 2020 |
| JJW Academy Limited | Education | 2020 |
| JK - Contractors Ltd | Construction | 2020 |
| JK Design (PVT) Limited | Wholesale & retail | 2021 |