| Horne Homes Ltd | Construction | 2004 |
| Horse Mischief Limited | Extraterritorial | 2017 |
| Horsefair Flats Ltd | Real estate | 2018 |
| Horseworld Trust | Professional & scientific | 2007 |
| Hot Spice Tandoori Limited | Hospitality | 2023 |
| HP Nails Limited | Other services | 2025 |
| HR & SA Limited | Hospitality | 2022 |
| HR Solutions and Services Ltd | Administrative & support | 2022 |
| HRC Design Ltd | Professional & scientific | 2020 |
| Huggins Foods Limited | Transport & logistics | 2009 |
| Hughes Engineering Limited | Manufacturing | 2025 |
| Hugofox Ltd | Information & communication | 1999 |
| Hursley Hill Garage (Bristol) Limited | Wholesale & retail | 1988 |
| Hvac Units Limited | Energy | 2025 |
| Hype Hair Whitchurch Ltd | Other services | 2011 |
| I & D Motor Services Ltd | Wholesale & retail | 2011 |
| I Bartlett Holdings Limited | Financial services | 2026 |
| Icda Awards Ltd | Administrative & support | 2020 |
| IF YOU Dare Ltd | Wholesale & retail | 2025 |
| Ightfield Developments Limited | Extraterritorial | 2015 |
| Ikonyx Limited | Manufacturing | 2001 |
| Ilkeston Propco Limited | Real estate | 2025 |
| Imageprove.Com Limited | Manufacturing | 2001 |
| Imjo Properties Ltd | Real estate | 2022 |
| IML Marine Management Limited | Transport & logistics | 1986 |
| Inmylocker Limited | Other services | 2013 |
| Innerspace (Cheshire) Limited | Wholesale & retail | 2006 |
| Innerspace Properties Limited | Households | 2016 |
| Input Squared Limited | Information & communication | 2012 |
| Insafehands Limited | Health & social care | 2010 |
| Insight Marketing Consultancy Limited | Professional & scientific | 2005 |
| Inspired Mindset Ltd | Education | 2020 |
| Instant Rain Limited | Administrative & support | 2020 |
| Instantix Limited | Other services | 2006 |
| Insurdio Ltd | Professional & scientific | 2022 |
| Insyncdesign Limited | Information & communication | 2009 |
| Intercontrol Limited | Wholesale & retail | 2002 |
| Intime Surgical Services Ltd | Health & social care | 2016 |
| Iolight Limited | Manufacturing | 2014 |
| Ipswich Speedway Limited | Arts & recreation | 1950 |
| Iptcp Ltd | Information & communication | 2015 |
| Iscoyd Doggy Daycare Ltd | Other services | 2023 |
| Iscoyd Estate Company,(The) | Real estate | 1924 |
| IT Liferaft Limited | Information & communication | 2024 |
| IT Zone(U.K.) Limited | Manufacturing | 2003 |
| ITA Logistics Ltd | Transport & logistics | 2020 |
| Italian Cuisine Limited | Hospitality | 2013 |
| Ivitalis Ltd | Administrative & support | 2022 |
| J & J Autos Limited | Wholesale & retail | 2022 |
| J & J Projects (South Wales) Limited | Construction | 2017 |
| J & R Millington Limited | Wholesale & retail | 2018 |
| J H Dimelow Limited | Construction | 2016 |
| J Holdings Midlands Limited | Construction | 2022 |
| J Leedham Ltd | Professional & scientific | 2024 |
| J P Burton Ltd | Public administration | 2016 |
| J&L NDT Ltd | Professional & scientific | 2022 |
| Jaffrey Media Group Limited | Information & communication | 2025 |
| Jaicae Limited | Construction | 2019 |
| Jake Gurr Financial Services Limited | Professional & scientific | 2018 |
| James Evans Sound Limited | Information & communication | 2023 |
| Jarr Property Management Limited | Real estate | 2024 |
| Jawline Limited | Information & communication | 2020 |
| Jbsalesuk Ltd | Wholesale & retail | 2022 |
| JC Rents Ltd | Financial services | 2025 |
| JCL Coffee Shop Ltd | Hospitality | 2024 |
| Jcosti Limited | Administrative & support | 2023 |
| JCP Kitchen and Bedroom Interiors Limited | Other services | 2023 |
| Jcsr Investments Ltd | Real estate | 2025 |
| JD Ecosolutions Ltd | Water & waste | 2022 |
| JD Legal Accounts Limited | Professional & scientific | 2025 |
| Jdotech Limited | Professional & scientific | 2025 |
| JEC Kick-Boxing Limited | Education | 2024 |
| JEN Rainsford Mortgage Services Ltd | Financial services | 2019 |
| Jenact Limited | Professional & scientific | 1997 |
| Jenton International Limited | Manufacturing | 1975 |
| Jess Lavers Design Limited | Other services | 2012 |
| JF & HE Mullock Limited | Agriculture & fishing | 2011 |
| Jitpals UK Ltd | Professional & scientific | 2021 |
| JJ Construction Midlands Limited | Construction | 2022 |
| JLD Prestige Limited | Other services | 2022 |
| JLS Carpentry & Build Ltd | Construction | 2025 |
| Jmca Research (UK) Ltd | Professional & scientific | 2016 |
| JMP Crusher Repairs Ltd | Manufacturing | 2008 |
| Joanne Hughes Driver Ltd | Transport & logistics | 2025 |
| John Gibbs Partnership Limited | Professional & scientific | 2005 |
| John Warburton-Lee Photography Limited | Arts & recreation | 2009 |
| Joli Cafe Ltd | Hospitality | 2025 |
| Joli Traditional Spanish Coffee Shop Ltd | Administrative & support | 2021 |
| Joliver Ltd | Information & communication | 2020 |
| Jolly Gardeners Limited | Administrative & support | 2022 |
| JON Wilks Digital Ltd | Information & communication | 2021 |
| Josam Properties Ltd | Real estate | 2026 |
| Josman Limited | Professional & scientific | 2003 |
| Joypolloi Music Ltd | Arts & recreation | 2023 |
| JP Roofing & Groundworks Ltd | Construction | 2024 |
| JPU Construction Ltd | Construction | 2023 |
| JPW Carpentry Limited | Construction | 2016 |
| JS Technical Limited | Professional & scientific | 2019 |
| JSX Communications Ltd | Professional & scientific | 2019 |
| JT Huxley Ltd | Agriculture & fishing | 2023 |