| Harlestone Developments Limited | Construction | 2018 |
| Harlestone Home Care Ltd | Health & social care | 2014 |
| Harlestone Property Limited | Households | 2014 |
| Harlestone Restoration Ltd | Manufacturing | 2025 |
| Harley Investments Limited | Real estate | 2023 |
| Harley RAE GAS Limited | Manufacturing | 2017 |
| Harley Street Skin Limited | Administrative & support | 2009 |
| Harlun Limited | Wholesale & retail | 2016 |
| Harlyn Enterprises Limited | Construction | 1975 |
| Harman Developments Limited | Construction | 2004 |
| Harmatan and Oakridge Leathers 2008 Limited | Manufacturing | 2008 |
| HARMINDER5 Limited | Other services | 2024 |
| Harmonious Goods Ltd | Wholesale & retail | 2026 |
| Harmony Community Care PVT Ltd | Health & social care | 2025 |
| Harnessing Potential Limited | Education | 2007 |
| Harper Properties (Northampton) Limited | Administrative & support | 2016 |
| Harper Services Limited | Construction | 2008 |
| Harpole Collage Ltd | Wholesale & retail | 2022 |
| Harpole News LLP | | 2016 |
| Harpolean Incorporated Ltd | Extraterritorial | 2021 |
| Harpur Crewe Ltd | Other services | 2020 |
| Harriet Kent Limited | Real estate | 2023 |
| Harriett Turner Responsible Business Consultancy Ltd | Administrative & support | 2020 |
| Harrington Farming Company Limited | Professional & scientific | 2004 |
| Harrington Farms Limited | Agriculture & fishing | 2004 |
| Harris & Clarke LLP | | 2008 |
| Harris & Co (Accountants) Limited | Professional & scientific | 2002 |
| Harris & Co (Audit) Ltd | Professional & scientific | 2016 |
| Harris CM Limited | Construction | 2008 |
| Harris Design Studio Ltd | Information & communication | 2008 |
| Harris Distribution Limited | Extraterritorial | 1962 |
| Harris Retail Solutions Limited | Wholesale & retail | 2012 |
| Harris “N” Hayes Limited | Wholesale & retail | 2019 |
| Harrison Architects + Designers Ltd | Professional & scientific | 2010 |
| Harrison Courier Services Limited | Administrative & support | 2018 |
| Harrison Electrical (Northampton) Limited | Construction | 2011 |
| Harrison MAY GEO Ltd | Construction | 2020 |
| Harrison MAY GEO Rental Properties Ltd | Real estate | 2022 |
| Harrison Prestige Ltd | Construction | 2025 |
| Harrisons Private Hire Ltd | Transport & logistics | 2024 |
| Harry Cutting Ltd | Other services | 2018 |
| Harry Wigram Property Limited | Real estate | 2018 |
| Hart Consulting Services Ltd | Professional & scientific | 2024 |
| Hart Information Solutions Limited | Administrative & support | 2015 |
| Hartflex Limited | | 1983 |
| Hartford Energy Consulting Limited | Professional & scientific | 2023 |
| Harting Limited | Manufacturing | 2005 |
| Harting Manufacturing UK Limited | Manufacturing | 2005 |
| Harting UK Limited | Professional & scientific | 1980 |
| Hartley Consultancy Limited | Professional & scientific | 2025 |
| Hartshill Care Ltd | Health & social care | 2022 |
| Hartwell & SON Limited | Construction | 2014 |
| Hartwell Primary School | Education | 2011 |
| Hartwell Safety Services Limited | Other services | 2012 |
| Harun's Barber Ltd | Other services | 2022 |
| Harun's Studio Ltd | Other services | 2023 |
| Haruns Bakery Ltd | Hospitality | 2023 |
| Harvest African Market Ltd | Wholesale & retail | 2025 |
| Harvest Moon Homes Limited | Real estate | 2023 |
| Harvest Print Media Ltd | Information & communication | 2013 |
| Harvey Electrics Ltd | Construction | 2025 |
| Harvey LEE Construction Ltd | Construction | 2021 |
| Harvey Lewis Group Limited | Financial services | 2023 |
| Harvey Lewis Holdings Limited | Financial services | 2015 |
| Harvey Thorneycroft Limited | Other services | 2006 |
| Harvig Healthcare Ltd | Health & social care | 2022 |
| Harvig Limited | Real estate | 2020 |
| Harworth Logistics Park Management Company Limited | Households | 2024 |
| Harwyn Ltd | Financial services | 1988 |
| HAS Barbers Ltd | Other services | 2018 |
| Hasac Limited | Real estate | 2008 |
| Hasch Ltd | Transport & logistics | 2017 |
| Haseeb Zahid Ltd | Wholesale & retail | 2025 |
| Hashtag Boom Limited | Wholesale & retail | 2014 |
| Hashtag Cars Ltd | Wholesale & retail | 2019 |
| Hashtag Justin Chef Ltd | Hospitality | 2020 |
| Hashtag Leader Ltd | Education | 2023 |
| Haskamena Ltd | Wholesale & retail | 2021 |
| Haslucks Green Road Limited | Construction | 2006 |
| Hassall Services Limited | Real estate | 2010 |
| Hatchbox Ltd | Administrative & support | 2023 |
| Hatfield Darlington Limited | Transport & logistics | 2020 |
| Hathaway Group Ltd | Transport & logistics | 2020 |
| Hathaway Holiday Lets Ltd | Hospitality | 2018 |
| Hatida Care Ltd | Public administration | 2025 |
| Hatimgonj Ltd | Hospitality | 2020 |
| Hatton Excel Consulting Ltd | Professional & scientific | 2026 |
| Hatton Goldsmiths Ltd. | Wholesale & retail | 2005 |
| Hatton Park Developments Ltd | Construction | 2020 |
| Haulage Force Ltd | Transport & logistics | 2018 |
| Haulage Hornets Ltd | Transport & logistics | 2024 |
| Hauraton Limited | Construction | 1995 |
| Hauriya Ltd | Wholesale & retail | 2025 |
| Haus of DK Ltd | Real estate | 2024 |
| Haus Properties (UK) Ltd | Real estate | 2025 |
| Hause of Beauty Ltd | Other services | 2025 |
| Havelock Recruit Ltd | Administrative & support | 2025 |
| Haven Care and Support Services Ltd | Health & social care | 2019 |
| Havenrise Homes Ltd | Financial services | 2024 |
| Haversley Holdings Ltd | Financial services | 2022 |