| HC1 Motors Ltd | Wholesale & retail | 2025 |
| HCC 2011 Limited | Professional & scientific | 1967 |
| Healthcare Waste Management Association Limited | Other services | 1992 |
| Hearnfield Management Limited | Households | 2012 |
| Heatherlands Residents Management Company Limited | Households | 2018 |
| Heathwood Park (Lindfield) Management Company Limited | Households | 2014 |
| Hebcom Ltd | Administrative & support | 2011 |
| Hedonia Property Ltd | Real estate | 2025 |
| Heene Court Mansions (Worthing) Limited | Households | 1990 |
| Heene Place Investments Limited | Real estate | 2019 |
| Helen Hoffman Consultancy Limited | Financial services | 2009 |
| Helios Property Services Limited | Real estate | 2017 |
| Helix Capital Limited | Administrative & support | 2018 |
| Helixena Limited | Information & communication | 2022 |
| Hennebry Limited | Wholesale & retail | 2011 |
| Henry Atticus Investments Limited | Real estate | 2018 |
| Henry White's House Limited | Households | 2022 |
| Heritage Art Company Limited | Arts & recreation | 2010 |
| Heritage Quay (NO.2) Management Company Limited | Extraterritorial | 2000 |
| Herne Court Residents Ltd. | Other services | 1993 |
| Heron Electric Company Limited | Manufacturing | 1995 |
| Heslewood Trading Limited | Arts & recreation | 2010 |
| Heybourn Property Group Ltd | Real estate | 2026 |
| Hidden Production Music Ltd | Information & communication | 2021 |
| High Breezes Management Limited | Households | 2014 |
| High Ideas Limited | Arts & recreation | 2016 |
| Highdown Agility Ltd | Other services | 2022 |
| Highswell Limited | Professional & scientific | 2008 |
| Highway Star Driver Training Ltd | Education | 2024 |
| Hilder Consultancy Ltd | Professional & scientific | 2021 |
| Hillbain Limited | Real estate | 2005 |
| Hillbrow Lodge Residential Management (Eastbourne) Limited | Real estate | 1999 |
| Hillsons Ltd. | Wholesale & retail | 2001 |
| Hillview Hideaway Ltd | Real estate | 2020 |
| Historic Sussex Hotels Limited | Administrative & support | 1998 |
| Hitek DB Pension Scheme Trustees Ltd | Professional & scientific | 2017 |
| Hitek Power Limited | Manufacturing | 1967 |
| Hive Assets Holdings Ltd | Financial services | 2023 |
| Hive Assets Ltd | Construction | 2019 |
| HK Autonomy Ltd | Professional & scientific | 2025 |
| HM Landscaping Ltd | Administrative & support | 2024 |
| Hoang Signature Ltd | Other services | 2024 |
| Holidaysgo Limited | Administrative & support | 2017 |
| Home Priority Group Ltd | Manufacturing | 2013 |
| Homebliss Care Limited | Health & social care | 2025 |
| Homely Bites Ltd | Hospitality | 2026 |
| Homes 4 ALL Lettings Ltd | Real estate | 2019 |
| Homestead Freeholders Limited | Households | 2000 |
| Homestead Residents' Association Limited (the) | Households | 1971 |
| Hopkins Building & Carpentry Limited | Construction | 2014 |
| Horizon Intercontinental Ltd | Wholesale & retail | 2019 |
| Horizon Recordings Limited | Information & communication | 2013 |
| Hot Pizza Ltd | Hospitality | 2019 |
| Howard Penrose Limited | Real estate | 2025 |
| Howgate House Ltd | Construction | 2024 |
| HRD 2010 Limited | Professional & scientific | 1986 |
| HSH Hotels (2017) Limited | Administrative & support | 2017 |
| Hugo Luis Jewellery Ltd | Manufacturing | 2021 |
| Humed Ltd | Health & social care | 2011 |
| Humphreys Houses Limited | Real estate | 2025 |
| Hundred HUT Productions Limited | Information & communication | 2015 |
| Hunston Homes Ltd | Construction | 2025 |
| Hunter's Place Residents Management Company Limited | Households | 2013 |
| Hunters Close (Flats) Limited | Households | 1974 |
| Hurcheon Limited | Information & communication | 2011 |
| Hyde Court (Eastbourne) Limited | Households | 2001 |
| HZ Houses Ltd | Real estate | 2024 |
| I H Roofing Services Limited | Construction | 2015 |
| Iberica Delicatessen Ltd | Wholesale & retail | 2004 |
| Ibex Supplies Limited | Wholesale & retail | 2017 |
| Ibrahim Kebab Limited | Hospitality | 2025 |
| IBS Consultants Limited | Professional & scientific | 2010 |
| Ice Beer Van Ltd | Wholesale & retail | 2020 |
| Icespark Limited | Households | 1985 |
| Identivue Limited | Information & communication | 2001 |
| Iflb Limited | Arts & recreation | 2016 |
| Image Barber Ltd | Other services | 2016 |
| Imperium Corporate Finance Limited | Financial services | 2009 |
| IN the Shadows Ltd | Information & communication | 2018 |
| Inaya East Preston Ltd | Hospitality | 2025 |
| INC1973 Limited | Professional & scientific | 2013 |
| Incendiary Design Ltd | Information & communication | 2023 |
| Indigoeden Consulting Ltd | Information & communication | 2007 |
| Indoor Cricket Centre Littlehampton Ltd | Arts & recreation | 2024 |
| Indoor Padel Centre Ltd | Arts & recreation | 2025 |
| Informed Design Consulting Ltd | Professional & scientific | 2012 |
| Injection Moulding Solutions Ltd | Professional & scientific | 2019 |
| INK Trader Limited | Wholesale & retail | 2011 |
| Innes Technical Engineering Limited | Information & communication | 1995 |
| Inpress Group Holding Ltd | Financial services | 2024 |
| Inpress Precision Ltd | Manufacturing | 1998 |
| Inside OUT Interiors Limited | Construction | 2025 |
| Insignia Plus Ltd | Wholesale & retail | 2011 |
| Inspirational Creations Limited | Wholesale & retail | 2025 |
| Inspirational Seminars Limited | Financial services | 2007 |
| Inspire Property (JK) Ltd | Construction | 2010 |
| Insulated Render Systems Limited | Construction | 2013 |
| Intech Calibration Limited | Professional & scientific | 2001 |
| Interfurb Refurbishments Ltd | Construction | 2012 |
| Interlink Packaging (UK) Limited | Administrative & support | 1998 |