| Hoppa Holdings Limited | Real estate | 2017 |
| House of Nail 96 Ltd | Other services | 2024 |
| Howard Dixon Associates Ltd | Wholesale & retail | 2017 |
| Howard Glendenning Land Management Contractors Limited | Agriculture & fishing | 2025 |
| HRG OIL & GAS Consulting Ltd | Professional & scientific | 2021 |
| HUG GEO Limited | Wholesale & retail | 2023 |
| Hughes and Co Properties Ltd | Hospitality | 2022 |
| Hull (T) Hairdressing Limited | Other services | 2014 |
| Humbly Grove Energy Limited | Mining & quarrying | 2003 |
| Humbly Grove Energy Services Limited | Energy | 2004 |
| Hummingbird Foods Limited | Wholesale & retail | 2022 |
| Hummingbird Healing Fields Limited | Health & social care | 2024 |
| HUN Salon Ltd | Other services | 2021 |
| Hunters Mews Limited | Households | 2014 |
| Huntingfords Ltd | Professional & scientific | 2023 |
| Hustler Venture Partners Limited | Financial services | 1993 |
| Hydrosphere Limited | Professional & scientific | 2001 |
| Hydrosphere Navaids Limited | Extraterritorial | 2012 |
| Hydrosphere UK Limited | Wholesale & retail | 1994 |
| Hyphen Projects Limited | Construction | 2024 |
| I Broke My Phone Ltd | Wholesale & retail | 2019 |
| I C Gregory Electrical Services Limited | Construction | 2012 |
| I CEE Films Ltd | Other services | 2023 |
| I.P.P.S. Training Limited | Administrative & support | 2004 |
| I.T Mccarthy Investments Ltd | Real estate | 2023 |
| I2 Solutions Ltd | Wholesale & retail | 2014 |
| IAM Global Commerce Ltd | Wholesale & retail | 2025 |
| IAN Mcneill Horse Supplies Limited | Wholesale & retail | 1995 |
| IC Consultancy Services Limited | Professional & scientific | 2019 |
| IC Masterclass Ltd | Education | 2024 |
| Ice Machines UK Ltd | Wholesale & retail | 2002 |
| Icool Refrigeration and Air Conditioning Limited | Construction | 2014 |
| Ideal Electrical and Plumbing Supplies Limited | Wholesale & retail | 2010 |
| Ideal for Bathrooms Limited | Real estate | 2007 |
| Identity Document Validation Services Ltd | Other services | 2018 |
| Idrive Driving School Hampshire Ltd | Education | 2016 |
| IEP International Holdings Ltd | Other services | 2023 |
| IGM Limited | Professional & scientific | 2002 |
| Ignition Bidco Limited | Financial services | 2021 |
| Ihrdc - Invincible Energy Ltd | Professional & scientific | 2013 |
| ILC Security Solutions Limited | Professional & scientific | 2025 |
| Imega Culture and Education Company Ltd | Education | 2019 |
| Immersion Escape Rooms Ltd | Administrative & support | 2023 |
| Impact Sewing Machinery Limited | Administrative & support | 1994 |
| Imperium Pecuniam Limited | Professional & scientific | 2012 |
| Impulse Software Limited | Information & communication | 1994 |
| IN a BIT Limited | Manufacturing | 2025 |
| IN Rounders LLP | | 2020 |
| In-Space Missions Limited | Manufacturing | 2015 |
| Inca Road Customs Ltd | Wholesale & retail | 2022 |
| Inca Road Sales Limited | Wholesale & retail | 2026 |
| Independent Midwife Limited | Health & social care | 2013 |
| Indiya Spice Ltd | Hospitality | 2026 |
| Infinexy Limited | Information & communication | 2020 |
| Infoaktiv Ltd | Information & communication | 2007 |
| Infoaktiv Studios Ltd | Information & communication | 2020 |
| Inform Limited | Information & communication | 2013 |
| Ingrad Systems Limited | Information & communication | 1986 |
| Ingu Limited | Information & communication | 2018 |
| Innovia Design Limited | Other services | 1996 |
| Inotio Limited | Professional & scientific | 2024 |
| Input Performance AI Ltd | Information & communication | 2025 |
| Input Performance Ltd | Arts & recreation | 2024 |
| Insert Consulting Ltd | Information & communication | 2020 |
| Inside View Limited | Information & communication | 1995 |
| Inspiration Finance Limited | Financial services | 2011 |
| Inspirational Gifting Limited | Wholesale & retail | 2024 |
| Inspired Minds International Ltd | Health & social care | 2006 |
| Inspired Mortgages Ltd | Financial services | 2012 |
| Instyle Services Limited | Other services | 1998 |
| Insurance Management Consultants Limited | Administrative & support | 2020 |
| Intamac Packaging Systems Limited | Professional & scientific | 1950 |
| Integral Growth Limited | Professional & scientific | 2019 |
| Integrated Satellite Telecommunications PLC | Financial services | 2000 |
| Intelligent Immersion Limited | Wholesale & retail | 2012 |
| Intelligent Things Ltd | Wholesale & retail | 2017 |
| Interbellum Films Ltd | Information & communication | 2024 |
| Intercreative Ltd | Information & communication | 2021 |
| Intermedia Production Ltd | Information & communication | 2024 |
| International Software Technologies Ltd | Information & communication | 2012 |
| Intertec (Electronics) Limited | Manufacturing | 1976 |
| Intraframe Ltd | Other services | 2024 |
| Investwise Properties Solutions Ltd | Real estate | 2024 |
| ION Power Limited | Administrative & support | 2018 |
| Iota London Ltd. | Wholesale & retail | 2014 |
| Iqbal Ecommerce Ltd | Wholesale & retail | 2023 |
| Islington (T) Hairdressing Limited | Other services | 2016 |
| Isn'T IT Wonderful Ltd | Health & social care | 2025 |
| IT Leadership Ltd | Information & communication | 2023 |
| Itaste Catering Limited | Wholesale & retail | 2020 |
| Ivan Hayward Holdings Limited | Financial services | 2024 |
| J & B Water Services Limited | Construction | 2026 |
| J & J Brice Properties Limited | Real estate | 2020 |
| J & J Motor Services Limited | Wholesale & retail | 2019 |
| J a Assessment Limited | Administrative & support | 2015 |
| J a H M Trading Company Limited | Wholesale & retail | 2017 |
| J Taylor Building Limited | Construction | 2013 |
| J&F Linton Ltd | Health & social care | 2021 |
| J. W. Muggeridge & Sons Limited | Wholesale & retail | 1960 |
| J.L.Gray Roofing Ltd | Construction | 2025 |