| Heligroup Limited | Transport & logistics | 2016 |
| Heligroup Operations Limited | Transport & logistics | 2012 |
| Helios Helium Ventures UK Limited | Mining & quarrying | 2011 |
| Henley Food and Drink Ltd | Wholesale & retail | 2016 |
| Henley L1 Limited | Real estate | 2023 |
| Henley Media Investment Consulting Ltd | Professional & scientific | 2020 |
| Henry Sanderson & Co Limited | Administrative & support | 2009 |
| Henry Sanderson Interiors Ltd | Wholesale & retail | 2006 |
| Herbert & Webster Ltd | Financial services | 2010 |
| Heritage Chronicles Ltd | Professional & scientific | 2025 |
| Heritage Gardens Management Company Limited | Households | 2017 |
| Hero Stories Ltd | Information & communication | 2025 |
| Herons Place (Maidenhead) Management Company Limited | Households | 1999 |
| Herschel Management Limited | Professional & scientific | 2010 |
| Hewett Wealth Management Limited | Administrative & support | 2023 |
| HG Law Ltd | Professional & scientific | 2016 |
| Hibernia Home & Garden Ltd | Construction | 2026 |
| Hiero Clothing Ltd | Wholesale & retail | 2026 |
| High Beeches Management Company (Marlow) Limited | Real estate | 1989 |
| High Beeches Residents Company Limited | Households | 2020 |
| High Infinity Properties Ltd | Real estate | 2019 |
| Highfield Flat Owners Ltd | Households | 2002 |
| Highlands Residents Association Limited | Households | 1998 |
| Hilro Consulting Limited | Professional & scientific | 2003 |
| HIT Global Limited | Professional & scientific | 2022 |
| Hitcham Court Residents Management Company Limited | Households | 2014 |
| HLG Limited | Professional & scientific | 2008 |
| HLS Developments Limited | Construction | 2009 |
| HMF Property Limited | Real estate | 2015 |
| Hmta Holdings Limited | Financial services | 2025 |
| Hoarding Helpers Limited | Transport & logistics | 2025 |
| Hockey Futures | Education | 2016 |
| Holdings JC Ltd | Financial services | 2025 |
| Holland Business Services Limited | Professional & scientific | 2010 |
| Hollie Webb Limited | Administrative & support | 2016 |
| Hollywell Holdings Limited | Financial services | 2006 |
| Holtspur Management Company Limited | Households | 1991 |
| Home Counties Storage Systems Limited | Construction | 1995 |
| Home Farm Asset Management Limited | Real estate | 2018 |
| Home Park Marina Limited | Financial services | 1989 |
| Home Resource Ltd | Real estate | 2023 |
| Homes by Harlequin Carshalton Limited | Real estate | 2023 |
| Honey Bees Homes Ltd | Real estate | 2022 |
| HOP 3W Limited | Financial services | 2020 |
| Horner & Taylor Property Services Ltd. | Real estate | 2019 |
| Houndstooth Heritage Ltd | Wholesale & retail | 2026 |
| Housebuilding Solutions Limited | Construction | 2024 |
| HQI Limited | Professional & scientific | 2008 |
| Huckenden Residents Management Limited | Professional & scientific | 2013 |
| Hugg Earrings Ltd | Wholesale & retail | 2025 |
| Hughenden Quarter Management Company Limited | Households | 2014 |
| Human+Nature Ltd | Wholesale & retail | 2020 |
| Hurley Gate Management Limited | Households | 2005 |
| Hutchbrain Ltd | Professional & scientific | 2026 |
| Huxson Ltd | Professional & scientific | 2015 |
| Hyde 'N' Sneaks Limited | Wholesale & retail | 2022 |
| I.B. Secure Limited | Administrative & support | 2019 |
| I.G.G. (UK) Limited | Professional & scientific | 2013 |
| Iawa Labs CIC | Arts & recreation | 2018 |
| IB Talent Search Ltd | Administrative & support | 2024 |
| Ibtd Limited | Information & communication | 2016 |
| Iconium Film Ltd | Information & communication | 2026 |
| Iffley Close Residents' Association Limited | Households | 1980 |
| Ihealth Pharma Limited | Wholesale & retail | 2019 |
| Illumicrate Limited | Wholesale & retail | 2018 |
| IM Studio Limited | Professional & scientific | 2025 |
| Imnoss Limited | Information & communication | 2018 |
| Imnotok CIC | Health & social care | 2023 |
| Imola 1953 Holdings Limited | Financial services | 2023 |
| Impactful Authenticity Ltd | Professional & scientific | 2022 |
| Imperial Place Residents Management Company Limited | Households | 2007 |
| Imperial Wharf Residents Association Ltd | Households | 2024 |
| Imperium Electrical Solutions Limited | Construction | 2018 |
| Imperium Solutions Group Limited | Professional & scientific | 2025 |
| Improvement Skills Consulting Limited | Administrative & support | 2007 |
| IMR GAS, Heating and Plumbing Limited | Construction | 2017 |
| IN Klover Limited | Wholesale & retail | 2015 |
| IN2 Limited | Professional & scientific | 2025 |
| Incepta Pharma UK Limited | Manufacturing | 2015 |
| Indres House Residents Company Limited | Real estate | 1976 |
| Inductive Developments Limited | Real estate | 2007 |
| Indydog Consulting Ltd | Information & communication | 2026 |
| Indzine Ltd | Information & communication | 2001 |
| Infectopharm Ltd | Wholesale & retail | 2024 |
| Informed Software Ltd | Information & communication | 2013 |
| Ingleton 19 Main Street Ltd | Real estate | 2012 |
| Iniprops Limited | Real estate | 2014 |
| Inker Consulting Limited | Education | 2007 |
| Innominds Consulting Ltd | Information & communication | 2024 |
| Innovation AV Limited | Other services | 2006 |
| Innovatise Limited | Information & communication | 2011 |
| Innovative Artists Ltd | Arts & recreation | 2018 |
| Insideout Decorating Marlow Ltd | Construction | 2022 |
| Insider Services UK Limited | Information & communication | 2019 |
| Insite Track Ltd | Information & communication | 2008 |
| Inspired Production Music Ltd | Professional & scientific | 2006 |
| Intellisoftech Limited | Information & communication | 2012 |
| Interglobal International Limited | Transport & logistics | 2000 |
| International Connections Limited | Professional & scientific | 2003 |
| International Consulting and Transformation Network LLP | | 2018 |