| Hong Kong House 2018 Ltd | Hospitality | 2018 |
| Horace HOG Limited | Manufacturing | 2025 |
| Horsfall International Limited | Construction | 1992 |
| Hourmarket Ltd | Information & communication | 2023 |
| Houseantiques Limited | Wholesale & retail | 2020 |
| Hoxton Bakehouse Group Limited | Financial services | 2020 |
| Hoxton Bakehouse Limited | Wholesale & retail | 2017 |
| Hoxton Bread Makers Limited | Manufacturing | 2014 |
| HPB Drywall Finishings Ltd | Construction | 2021 |
| Hundred Acre Kitchen Limited | Hospitality | 2023 |
| Hunt Telecommunications Limited | Professional & scientific | 2016 |
| Hunter Automotive Ltd. | Manufacturing | 2016 |
| Huntsgate Management Limited | Real estate | 2009 |
| I M Services Ltd | Transport & logistics | 2025 |
| I'M OK, You'Re OK Counselling and Training Limited | Health & social care | 2017 |
| Ianlin Ltd | Professional & scientific | 2022 |
| IC 360 Limited | Wholesale & retail | 1999 |
| ICM Property Limited | Real estate | 2024 |
| Iles and Vincent Funeral Services Limited | Other services | 2017 |
| Immerse Live Media Ltd | Arts & recreation | 2024 |
| Impeccable Home Improvements Ltd | Manufacturing | 2023 |
| IN the Room Festival Ltd | Arts & recreation | 2026 |
| Incor Services Limited | Professional & scientific | 2020 |
| Indico Media Limited | Information & communication | 2016 |
| Indoorgrowstore Ltd | Extraterritorial | 2013 |
| Information Assurance Management Solutions Ltd | Administrative & support | 2018 |
| Ingrid Hindle Notarial Services Ltd | Professional & scientific | 2022 |
| Inner Sky Ltd | Other services | 2015 |
| Innoimprove Ltd | Wholesale & retail | 2024 |
| Insight Processing Solutions Limited | Professional & scientific | 2025 |
| Invincipeople Ltd | Professional & scientific | 2014 |
| Iris and Olive Ltd | Wholesale & retail | 2019 |
| Isis Technologies Ltd | Manufacturing | 2010 |
| ISK Actuarial Ltd | Financial services | 2014 |
| Ivector Projects Ltd | Professional & scientific | 2026 |
| Iweyou Ltd | Professional & scientific | 2020 |
| Iylam Coaching and Consultancy Ltd | Professional & scientific | 2023 |
| J C Mailings Wiltshire Ltd | Information & communication | 2024 |
| J D Edmunds Limited | Professional & scientific | 2002 |
| J Dance Plumbing and Heating Ltd | Construction | 2024 |
| J L Sporting Ltd | Arts & recreation | 2012 |
| J M Stratton & Co Limited | Agriculture & fishing | 2019 |
| J R Meeker Dairy Limited | Agriculture & fishing | 2014 |
| J Robbins Solutions Limited | Professional & scientific | 2024 |
| J&D Prestige Vehicle Hire Ltd | Administrative & support | 2017 |
| J&R Building Services (SW) Ltd | Construction | 2024 |
| J&S Properties and Maintenance Ltd | Real estate | 2021 |
| JA Rail OPS Ltd | Professional & scientific | 2024 |
| Jaccbox Ltd | Information & communication | 2014 |
| Jakecation Limited | Real estate | 2025 |
| James Alexander Fine Foods Limited | Administrative & support | 2008 |
| James Greenlees Limited | Professional & scientific | 1996 |
| James Oborne Services Limited | Information & communication | 2012 |
| Jellyfish Property Investments Ltd | Real estate | 2026 |
| Jenham Transport Management Limited | Transport & logistics | 2014 |
| Jennifer Medhurst Limited | Information & communication | 2021 |
| Jess LEE Production Ltd | Administrative & support | 2022 |
| Jessup Plumbing & Heating Ltd | Construction | 2023 |
| JHS (LF) Limited | Agriculture & fishing | 2004 |
| Jiggyjaw Private IT Ltd | Information & communication | 2026 |
| JJO Fencing & Gardening Ltd | Administrative & support | 2017 |
| JL Productions Ltd | Information & communication | 2026 |
| JN87 Consulting Limited | Professional & scientific | 2017 |
| JOG IT on Limited | Information & communication | 2019 |
| John E.S. Jones & SON Ltd | Construction | 2007 |
| JON Green Fitness Studios Limited | Other services | 2015 |
| Jonca Limited | Real estate | 2000 |
| Jones GH Limited | Professional & scientific | 2025 |
| Josh Trim Design Limited | Arts & recreation | 2020 |
| Jrmc Security Limited | Administrative & support | 2024 |
| JS Access & Blade Services Ltd | Construction | 2020 |
| JSB Clinical Consulting Limited | Administrative & support | 2014 |
| Judospace Limited | Arts & recreation | 2009 |
| Jules PR Ltd | Professional & scientific | 2015 |
| Julex Construction Ltd | Construction | 2023 |
| Juodaky Properties Ltd | Real estate | 2024 |
| Just the Look Ltd | Wholesale & retail | 2015 |
| K Masterton Ltd | Information & communication | 2010 |
| K&R Farming Ltd | Agriculture & fishing | 2022 |
| Kameleon Collectables Ltd | Wholesale & retail | 2026 |
| Kameleon Vintage Ltd | Wholesale & retail | 2024 |
| Kate Pink Dental Hygiene & Therapy Ltd | Health & social care | 2009 |
| KCF UK (Kids Come First) C.I.C. | Other services | 2015 |
| Keepers Cottage Crafts Ltd | Arts & recreation | 2025 |
| Keller Auto Restoration Ltd | Wholesale & retail | 2023 |
| Keller Auto Restore Ltd | Wholesale & retail | 2023 |
| Kellow Woodcraft Limited | Manufacturing | 2023 |
| Kelshall Plastics Limited | Water & waste | 2006 |
| Kemble Business Park LLP | | 2006 |
| Kemble Park Management Company Limited | Administrative & support | 2001 |
| Kenneth Spencer Limited | Agriculture & fishing | 1957 |
| Keystone Masonry (Bristol) Limited | Construction | 2006 |
| Kilner Osteopathy Ltd | Health & social care | 2020 |
| Kinder Timber Products Limited | Wholesale & retail | 2014 |
| Kinghay Investments Limited | Real estate | 1995 |
| Kings Court (Market Lavington) Limited | Households | 2013 |
| Kingston Court Four Oaks Limited | Real estate | 1994 |
| Kingstone Contractors Limited | Real estate | 2005 |
| Kinovo Fitness Ltd | Arts & recreation | 2025 |
| Kubale Consulting Ltd | Professional & scientific | 2025 |