| J Miller Plumbing and Heating Ltd | Construction | 2024 |
| J P Paint & Build Ltd | Construction | 2025 |
| J P Property Supplies Limited | Construction | 2024 |
| J Sutton Driveways Ltd | Construction | 2019 |
| J Sutton Landscapes Ltd | Administrative & support | 2019 |
| J&J Networking Co. Ltd | Administrative & support | 2008 |
| Jaadu Limited | Wholesale & retail | 2009 |
| Jace Properties (South East) Limited | Real estate | 2025 |
| Jackie Milton Students Limited | Administrative & support | 2011 |
| Jacob Matthews Property Ltd | Real estate | 2018 |
| JAM Statics Ltd | Wholesale & retail | 2023 |
| Jamberry Limited | Professional & scientific | 1997 |
| James Andrews Golf School Limited | Administrative & support | 2017 |
| Jane Mather Limited | Other services | 2005 |
| Jayne Hancock Limited | Information & communication | 2013 |
| JB Prints Ltd | Manufacturing | 2023 |
| JC Mechanical Ltd | Construction | 2021 |
| Jcare Healthy Home Limited | Administrative & support | 2022 |
| Jcare Recruitment (GB) Ltd | Administrative & support | 2024 |
| Jcare(Gb) Ltd | Administrative & support | 2021 |
| Jcats Limited | Professional & scientific | 2008 |
| JDC Assets Ltd | Real estate | 2025 |
| Jekyll and Clyde Productions Limited | Information & communication | 2013 |
| Jellyfish Swim School Ltd | Education | 2025 |
| Jennings Calloway Limited | Administrative & support | 2020 |
| JF Hires Ltd | Arts & recreation | 2025 |
| JFS Commercial Ltd | Real estate | 2022 |
| JFS Properties (Bexhill) T/A JFS Properties Ltd | Real estate | 2018 |
| Jiastone (Land) Ltd | Real estate | 2023 |
| Jiastone Limited | Financial services | 2014 |
| Jigsaw Energy Ltd | Construction | 2021 |
| Jigsaw Group Limited | Financial services | 2021 |
| JIM Philcox Estate Agents Ltd | Real estate | 2021 |
| Jim's Kitchen Ltd | Hospitality | 2026 |
| Jimmy Broadbent Media Ltd | Professional & scientific | 2019 |
| JJ Olney Property Limited | Real estate | 2024 |
| Jj's Commercial Cleaning Services Ltd | Administrative & support | 2026 |
| JKC Group Holdings Limited | Financial services | 2025 |
| JLB Accountants Ltd | Professional & scientific | 2026 |
| Jlbassfield Limited | Health & social care | 2021 |
| Jlex Networks Limited | Information & communication | 2011 |
| JLM Assets LLP | | 2016 |
| JLM Investment Assets Limited | Other services | 2016 |
| JMA Associates (ST Leonards) Limited | Real estate | 2008 |
| Jmmc Properties Limited | Construction | 2016 |
| JN Homes Ltd | Real estate | 2019 |
| Joey Productions Ltd | Information & communication | 2013 |
| John Campbell Carpentry and Building Ltd | Construction | 2017 |
| Jolla Ltd | Wholesale & retail | 2019 |
| Josh Powell Music Limited | Information & communication | 2012 |
| Joule Arts and Events Limited | Professional & scientific | 2015 |
| JP Global Projects Ltd | Professional & scientific | 2021 |
| JRN Property Ltd | Real estate | 2021 |
| JS Yachting Ltd | Wholesale & retail | 2021 |
| JT Production Engineering Limited | Administrative & support | 2015 |
| JT Restoration Ltd | Construction | 2022 |
| JTB Services Ltd | Construction | 2022 |
| JTK Mechanical Management Ltd | Construction | 2023 |
| Jubar Limited | Real estate | 1961 |
| Jubilee Court Care Ltd | Health & social care | 2017 |
| Just Catering Repairs Limited | Manufacturing | 2023 |
| Just for Accountants Limited | Professional & scientific | 2003 |
| Just the Books Ltd | Wholesale & retail | 2019 |
| Justbeuberoo Ltd | Transport & logistics | 2025 |
| Justin Pierce Limited | Professional & scientific | 2015 |
| JW Safety Solutions Ltd | Information & communication | 2023 |
| JWH Enterprises Limited | Wholesale & retail | 2021 |
| K Barden Limited | Wholesale & retail | 2016 |
| K J Hudson Content Ltd | Professional & scientific | 2020 |
| K K C Aesthetics UK Ltd | Wholesale & retail | 2025 |
| K-Tech Supplies Ltd | Manufacturing | 2008 |
| Kalhei Chicken Ltd | Hospitality | 2025 |
| Kalibrate Limited | Wholesale & retail | 2009 |
| Kalyoncu Properties Ltd | Real estate | 2022 |
| Kamil Frankowski Limited | Wholesale & retail | 2016 |
| Kangaroo Connections Limited | Professional & scientific | 2022 |
| Kara Civil Engineering Limited | Construction | 2010 |
| Karacaoglan Meat Ltd | Wholesale & retail | 2025 |
| Kartesh London Ltd | Manufacturing | 2025 |
| Kasi Motors Ltd | Professional & scientific | 2026 |
| KBE Capital Limited | Administrative & support | 2003 |
| KBO Design Ltd | Professional & scientific | 2016 |
| Kbob Holdings Limited | Real estate | 2021 |
| Kedslie Anderson Limited | Administrative & support | 2017 |
| Kelly Carers Limited | Health & social care | 2025 |
| Kemp Architecture Limited | Professional & scientific | 2021 |
| Kemporium Ltd | Real estate | 2023 |
| KEN Edwards Limited | Professional & scientific | 2008 |
| Kenilworth Tenants Association Limited | Households | 1996 |
| Kent Entertainment Ltd | Arts & recreation | 2013 |
| Kent Entertainment Properties Limited | Real estate | 2020 |
| Kent Entertainment Recruitment Ltd | Administrative & support | 2013 |
| Kentsussex Connect Ltd | Real estate | 2023 |
| Kewhurst Manor Limited | Households | 1993 |
| Keymer Carpentry & Construction Limited | Construction | 2016 |
| KHF Enterprises Ltd | Administrative & support | 2021 |
| Kiki Acquisitions Limited | Real estate | 2023 |
| Kiki Media Ltd | Professional & scientific | 2020 |
| Kindbridge Limited | Administrative & support | 2025 |
| King's Hollow LLP | | 2023 |