| Hand Tools City Ltd | Wholesale & retail | 2025 |
| Handcrafted by K and K Limited | Manufacturing | 2023 |
| Handen Consulting Limited | Information & communication | 1992 |
| Handley Bespoke Ltd | Manufacturing | 2024 |
| Handmade Creations Limited | Manufacturing | 2013 |
| Hands on Landscapes Limited | Administrative & support | 2010 |
| Handymansouthampton Ltd | Construction | 2023 |
| Hanex UK Limited | Wholesale & retail | 2019 |
| Hangar 49 Group Limited | Financial services | 2016 |
| Hangar One Aviation Systems Ltd | Professional & scientific | 2021 |
| Hanging Garden Limited | Administrative & support | 1990 |
| Hangman Capital Ltd | Administrative & support | 2024 |
| Hanley Castle Barns Ltd | Real estate | 2012 |
| Hannager Limited | Administrative & support | 2012 |
| Hannah Aesthetics RN Ltd | Wholesale & retail | 2023 |
| Hannah Davey Photography Ltd | Professional & scientific | 2026 |
| Hannah Evelyn Photography Ltd | Real estate | 2025 |
| Hannah Stodel Racing Limited | Transport & logistics | 2017 |
| Hannahs Home Help Ltd | Administrative & support | 2017 |
| Hannan Driving School Ltd | Education | 2025 |
| Hannan Plumbing & Heating Ltd | Construction | 2018 |
| Hannides & Co Limited | Professional & scientific | 2011 |
| Hannides Investments Limited | Real estate | 2006 |
| Hanovate Consultancy Ltd | Professional & scientific | 2024 |
| Hans Jensen Engineering Limited | Transport & logistics | 2021 |
| Hansen Shipping (UK) Limited | Transport & logistics | 2014 |
| Hansweethome Limited | Wholesale & retail | 2025 |
| Hantec Limited | Professional & scientific | 2019 |
| Hantec Systems Limited | Professional & scientific | 2001 |
| Hants Auto Fuels Limited | Wholesale & retail | 2003 |
| Hants Healthcare Limited | Health & social care | 2016 |
| Hants Imports Ltd | Wholesale & retail | 2022 |
| Hants Investments Limited | Professional & scientific | 2021 |
| Hants Properties Ltd | Households | 2018 |
| Hants Syed IT Consultant Limited | Professional & scientific | 2017 |
| Hants Transportation Ltd | Real estate | 2020 |
| Hants Tutoring and Childcare Services Limited | Health & social care | 2017 |
| Hanzx Ltd | Wholesale & retail | 2026 |
| HAO BAO Limited | Wholesale & retail | 2022 |
| HAP Properties Limited | Real estate | 2017 |
| Happy Bunnies Pre-School(Southampton) | Education | 2007 |
| Happy Care Home Limited | Health & social care | 2026 |
| Happy Cash Ltd | Construction | 2019 |
| Happy Companies Ltd | Financial services | 2016 |
| Happy Hearts Day Nursery Ltd | Education | 2011 |
| Happy Hot TUB Limited | Professional & scientific | 2006 |
| Happy Hounds Walks Ltd | Other services | 2025 |
| Happy House Cuisine Limited | Hospitality | 2023 |
| Happy Hungarian Mums CIC | Health & social care | 2025 |
| Happy LE Ltd | Hospitality | 2025 |
| Happy Lemon Southampton Limited | Hospitality | 2021 |
| Happy Oddity Ltd | Information & communication | 2024 |
| Happy Panda Chinese Ltd | Hospitality | 2025 |
| Happy Telemarketing Ltd | Administrative & support | 2021 |
| Happy Union Limited | Wholesale & retail | 2019 |
| Happy Valley Homes Ltd | Real estate | 2025 |
| Happy Valley Properties ( Hants ) Limited | Other services | 2020 |
| Happy-Helpful-Company Ltd | Water & waste | 2025 |
| Happytochase Ltd | Administrative & support | 2024 |
| Harbinger Riffs Ltd | Wholesale & retail | 2023 |
| Harbour & Jones Limited | Hospitality | 2004 |
| Harbour & Sky Ltd | Wholesale & retail | 2026 |
| Harbour Board Office Limited | Real estate | 2022 |
| Harbour by Selene Limited | Hospitality | 2024 |
| Harbour Homes Leasing Ltd | Real estate | 2026 |
| Harbour Lights Cinema Limited | Financial services | 2018 |
| Harbour View (Hythe) Management Company Ltd | Households | 2025 |
| Harbour View (Hythe) Mgmt Co Limited | Households | 2025 |
| Harbour Wealth Planning Limited | Professional & scientific | 2024 |
| Harbour Yachting Limited | Real estate | 2012 |
| Harbourvr Ltd | Health & social care | 2019 |
| Harcourt Mansions Freehold Limited | Households | 2023 |
| Hardcastle & Co Estates Limited | Real estate | 2025 |
| Hardcastle Hospitality Ltd | Hospitality | 2025 |
| Hardi Electrical Limited | Construction | 2021 |
| Hardison Developments Ltd | Construction | 2022 |
| Hardway Construction Limited | Construction | 2000 |
| Harestock Spice Limited | Hospitality | 2016 |
| Harfields Kennels Ltd | Other services | 2022 |
| Hargreaves Accountants LLP | | 2024 |
| Hargreaves and Co Ltd | Administrative & support | 2010 |
| Hargreaves Gabbana & Hameed Investments Ltd | Real estate | 2021 |
| Hargroves Property LLP | | 2015 |
| Hargunconstuction Ltd | Construction | 2025 |
| Haribel Ltd | Real estate | 2019 |
| Hariharan Constructions Ltd | Construction | 2025 |
| Harinam Properties Limited | Real estate | 2024 |
| Harissons PVT. Ltd | Wholesale & retail | 2025 |
| Harith Estates Limited | Real estate | 2021 |
| Harjay Limited | Real estate | 2025 |
| Harkins Homes Ltd | Real estate | 2018 |
| Harle Property Ltd | Households | 2025 |
| Harley BOY (Newcastle) Limited | Wholesale & retail | 2021 |
| Harley Court Management Hampshire Limited | Real estate | 2015 |
| Harley Street Consulting Rooms Limited | Administrative & support | 2014 |
| Harley Street Shockwave and Rejuvenation Clinic Limited | Administrative & support | 2016 |
| Harleys Smokehouse Limited | Hospitality | 2015 |
| Harman Carpentry Southern Ltd | Manufacturing | 2022 |
| Harmax Property Limited | Real estate | 2017 |
| Harmonia Medical Limited | Health & social care | 2018 |