| IA Mech Engineering Ltd | Construction | 2025 |
| IDE Vision Limited | Manufacturing | 2020 |
| Ideafreaks Ltd | Professional & scientific | 2003 |
| Idelete Ltd | Transport & logistics | 2012 |
| Igs-Digital Ltd | Wholesale & retail | 2019 |
| Ikbr Ltd | Manufacturing | 2018 |
| Iles Groundworks and Civil Engineering Ltd | Construction | 2018 |
| Illustrious Coven Ltd | Information & communication | 2024 |
| Iltg Ltd | Construction | 2023 |
| Iluli Ltd | Administrative & support | 2009 |
| Image Signs & Print Ltd | Manufacturing | 2012 |
| Imao (NPT) Limited | Hospitality | 2021 |
| Imperial Haulage Ltd | Transport & logistics | 2025 |
| Impla Ltd | Wholesale & retail | 2016 |
| Indian Empire Limited | Hospitality | 2006 |
| Injection Consulting Limited | Professional & scientific | 2015 |
| INK and Scribbles Limited | Education | 2022 |
| Instructor MAX Ltd | Education | 2023 |
| Instyle Leathergoods Limited | Manufacturing | 1980 |
| Insuliner Limited | Wholesale & retail | 1997 |
| Intelligent Quality Ltd | Information & communication | 2020 |
| International Graphic Supplies Ltd | Manufacturing | 2013 |
| International Quality Systems Ltd | Professional & scientific | 2017 |
| Intled Ltd | Education | 2023 |
| IP Audits Limited | Professional & scientific | 2023 |
| Isential Services Limited | Professional & scientific | 2012 |
| Itonline Ltd | Information & communication | 2019 |
| J Hughes Services Limited | Transport & logistics | 2018 |
| J Mccarthy Consulting Limited | Information & communication | 2020 |
| J.A.G. Electrical Solutions Ltd | Manufacturing | 2024 |
| J.A.W Consultancy Limited | Professional & scientific | 2023 |
| Jaga Group Ltd | Transport & logistics | 2021 |
| James Williams Builders Limited | Construction | 2023 |
| Jarlands Mortgage Specialists Ltd | Financial services | 2017 |
| JC Autel Limited | Wholesale & retail | 2011 |
| JD5 Properties Ltd | Real estate | 2023 |
| JED Scaffolding & Plant Limited | Construction | 1996 |
| Jemb NR Ltd | Hospitality | 2024 |
| Jesmac Limited | Construction | 2017 |
| JH Safety Consultancy Ltd | Professional & scientific | 2019 |
| JL 22 Limited | Transport & logistics | 2022 |
| JL Catering Ltd | Hospitality | 2024 |
| JLH Rendering & Property Ltd | Real estate | 2025 |
| JLP27 Ltd | Construction | 2024 |
| Jluk Ltd | Information & communication | 2022 |
| JME Plumbing & Heating Engineers Ltd | Construction | 2021 |
| JME Renewable Heating Ltd | Construction | 2022 |
| JMW E-Global Ltd | Professional & scientific | 2022 |
| JN Property Management Limited | Construction | 2025 |
| Jnrr Group Ltd | Professional & scientific | 2025 |
| Joanne Hume & SON Limited | Other services | 2014 |
| Joao Rodrigues Ltd | Health & social care | 2013 |
| Johndavidjohndaviddavidjohndavidson Ltd | Information & communication | 2024 |
| Jonathan George Harris Limited | Real estate | 2025 |
| Joops Works Ltd | Information & communication | 2026 |
| JPK Supplies Limited | Wholesale & retail | 2022 |
| Jude Rose Accountancy Limited | Professional & scientific | 2015 |
| Justdesygn Ltd | Professional & scientific | 2019 |
| JXS Core Ltd | Information & communication | 2024 |
| K75N78 Limited | Professional & scientific | 2002 |
| Kali Print Ltd | Manufacturing | 2020 |
| Kardinale Homes Limited | Construction | 2012 |
| Kardinale Investments Ltd | Real estate | 2018 |
| Kate Biddle Coaching Ltd | Other services | 2020 |
| Kavara Ltd | Construction | 2026 |
| KCA Prospects Ltd | Real estate | 2022 |
| KDM Building Ltd | Construction | 2021 |
| Keen Attachments Ltd | Manufacturing | 2012 |
| Kendall Construction Limited | Construction | 2025 |
| Keystone Management Systems Limited | Professional & scientific | 2025 |
| KG Fish Ltd | Hospitality | 2025 |
| Kids on Board Ltd | Wholesale & retail | 2026 |
| KJE Construction & Groundworks Ltd | Construction | 2023 |
| Kjii Property Ltd | Real estate | 2026 |
| KK Seagull Ltd | Other services | 2021 |
| KOB (Newport) Ltd | Hospitality | 2014 |
| Kolva Ltd | Information & communication | 2025 |
| KRE8TIVE Theatre Limited | Arts & recreation | 2019 |
| L C Mason Properties Limited | Real estate | 2022 |
| Lakshmi Medical Services Limited | Health & social care | 2022 |
| Lambardar Social Limited | Professional & scientific | 2024 |
| Land Rovers of Monmouthshire Limited | Wholesale & retail | 2020 |
| Launchway Ltd | Professional & scientific | 2018 |
| Laval & Co. Ltd | Real estate | 1997 |
| Laval Digital Ltd | Real estate | 2024 |
| Laval Estates Ltd | Real estate | 2010 |
| Laval Investments Ltd | Extraterritorial | 2024 |
| Lavarose Group Ltd | Wholesale & retail | 2020 |
| LDF Property Management Limited | Real estate | 2018 |
| Leaders of Tomorrow Ltd | Education | 2025 |
| Lemon Squeezy Creative Limited | Professional & scientific | 2021 |
| Leucott Properties Limited | Real estate | 2010 |
| Lexiscale Consulting Limited | Professional & scientific | 2024 |
| Life Media UK Limited | Information & communication | 2011 |
| Lifesciences Healthcare Limited | Administrative & support | 2010 |
| Lincaredirect Ltd | Health & social care | 2023 |
| Little Details Limited | Construction | 2016 |
| Live and LET Grow Limited | Administrative & support | 2014 |
| LIVE2LET Limited | Real estate | 2017 |
| Ljas Property Ltd | Real estate | 2024 |