| Harmon Group Limited | Manufacturing | 1998 |
| Harmon Metal Treatments Limited | Manufacturing | 2001 |
| Harmon Precision Grinding Limited | Manufacturing | 1998 |
| Harriet Mountjoy Book-Keeping Services Limited | Professional & scientific | 2006 |
| Harris & Nash Limited | Real estate | 1959 |
| Harrow Hill Properties Limited | Real estate | 1962 |
| Harvey's Surrey Limited | Other services | 2014 |
| Haskins Garden Centres Limited | Wholesale & retail | 1997 |
| Havenpool Investments Limited | Households | 1964 |
| Hayward Properties Limited | Real estate | 1949 |
| Hazlewood Court Freehold Limited | Households | 2006 |
| Hazlewood Court Management Company (Bournemouth) Limited | Households | 1988 |
| HD Products & Services Ltd | Manufacturing | 2025 |
| Headstart Financial Planning Limited | Financial services | 1999 |
| Heathcote Management Company Limited | Households | 1999 |
| Heatherbank Maintenance Company Limited | Households | 1958 |
| Helping Hands Domestic Care Limited | Health & social care | 2007 |
| Herbie Road Limited | Real estate | 2007 |
| Herstone Ltd | Real estate | 2005 |
| Heston General Cleaning Contractors Limited | Administrative & support | 1975 |
| HFC Trading Limited | Hospitality | 2018 |
| HG Arts Ltd | Wholesale & retail | 2008 |
| Hi-Q Installations Limited | Construction | 2007 |
| Hicklenton & Phillips Limited | Wholesale & retail | 1982 |
| High Profile (Dorset) Ltd | Construction | 2004 |
| Highbury Sourcing Ltd | Wholesale & retail | 2020 |
| Highdrive Property Co. Limited | Construction | 1966 |
| Hillcrest Surveys Limited | Professional & scientific | 2001 |
| Hillson & Co Ltd | Professional & scientific | 2003 |
| Hillview Pharmacy Limited | Wholesale & retail | 2003 |
| Hinton Estates Limited | Real estate | 2007 |
| Hippalus Ltd | Extraterritorial | 2022 |
| Hitch a Lift Ltd | Transport & logistics | 1998 |
| Hobbs Memorabilia Ltd | Wholesale & retail | 2022 |
| Hoburne Lane (Christchurch) Limited | Households | 2005 |
| Holcat Limited | Real estate | 2003 |
| Holdenhurst Court (Bournemouth) Limited | Households | 1996 |
| Hollington Agency Limited | Professional & scientific | 2006 |
| Holt House Management Limited | Households | 2000 |
| Home Necessary Limited | Wholesale & retail | 2025 |
| Home Plan (U.K.) Limited | | 1985 |
| Home-Start Wessex | Health & social care | 2005 |
| Homes to LET Limited | Construction | 2006 |
| Horizon Motor Company Limited | Wholesale & retail | 1971 |
| Horlock Developments (Poole) Limited | Real estate | 2005 |
| Horseman's Centre Limited (the) | | 1972 |
| Horsleys International Limited | Wholesale & retail | 2014 |
| Hospital Metalcraft Limited | Manufacturing | 1953 |
| Hotel Rembrandt Limited | Hospitality | 2006 |
| HPS DEV Co 3 Limited | Real estate | 2023 |
| Hudson-Cook Chiropractic Ltd | Health & social care | 2005 |
| Hump and Dump (Dorset) Limited | Water & waste | 2003 |
| Humphries Kirk Trustee Company | Professional & scientific | 1976 |
| Hunt's Foodservice (Bristol) Ltd | Wholesale & retail | 1965 |
| Hunt's Foodservice (Winchester) Ltd | Wholesale & retail | 1966 |
| Hunt’S Food Group Ltd | Wholesale & retail | 1974 |
| Hurfar Engineering Limited | Administrative & support | 2003 |
| Hutchings Bros. (Sea Food and Game) Limited | Wholesale & retail | 1974 |
| Hyperons Ltd | Information & communication | 1993 |
| I L S Southern Ltd | Construction | 2005 |
| I S Anderson Limited | Professional & scientific | 2005 |
| I2 Event Management Limited | Arts & recreation | 2000 |
| IAN Bruce Associates Limited | Real estate | 1984 |
| IAN Griffiths Ltd | Information & communication | 2007 |
| IAN W Wallace Limited | Financial services | 2007 |
| ICG Dynamics Ltd | Manufacturing | 2025 |
| Icream Consulting Limited | Health & social care | 2015 |
| ICT Global Limited | Administrative & support | 2007 |
| IKB Surveys Limited | Professional & scientific | 2001 |
| IKG Limited | Professional & scientific | 1996 |
| Imperial Dragon Limited | Hospitality | 2001 |
| Imperial Ecom Marketing Ltd | Information & communication | 2024 |
| Imsis Limited | Wholesale & retail | 2005 |
| IN Mind & Soul SON Ltd | Wholesale & retail | 2021 |
| Incredible Sims Limited | Information & communication | 2007 |
| Indi Entertainment Limited | Wholesale & retail | 2025 |
| Indian Nights Limited | Hospitality | 2002 |
| Indizendent Records Ltd | Information & communication | 2025 |
| Industrial Computing Limited | Information & communication | 1997 |
| Influxury Ltd | Information & communication | 2004 |
| Innoeffix UK Ltd | Wholesale & retail | 2025 |
| Insite Facilities Management Limited | Professional & scientific | 1990 |
| Integrated Business Management Systems Limited | Professional & scientific | 1999 |
| Intek Electronics UK Ltd | Wholesale & retail | 2006 |
| Intergage Labs Limited | Information & communication | 2023 |
| Intermarque Properties Limited | Real estate | 1996 |
| Interview Skills Clinic Limited | Information & communication | 2000 |
| Iron & Stone Limited | Wholesale & retail | 2002 |
| Island Motor Services Limited | Wholesale & retail | 2007 |
| IT Creative Solutions Ltd | Information & communication | 2006 |
| It's Time Limited | Information & communication | 1999 |
| Itcross Systems Limited | Information & communication | 2001 |
| Itkraft Limited | Information & communication | 1999 |
| Ivor Brooks Limited | Extraterritorial | 1964 |
| IW Roper Developments Limited | Construction | 1998 |
| J F Y Construction Limited | Construction | 2003 |
| J J Southgate Ltd | Health & social care | 2003 |
| J N4 U Limited | Manufacturing | 2007 |
| J Spiller & Sons Limited | Construction | 2003 |
| J&J Nexus Ltd | Wholesale & retail | 2025 |