| Hafod Gardens Management Co. Limited | Households | 1991 |
| Hafodrenys Valeting Ltd | Administrative & support | 2025 |
| Hafren Services Limited | Administrative & support | 2002 |
| Haft Trading Limited | Administrative & support | 2018 |
| Haillo Events Limited | Administrative & support | 2024 |
| Haines Watts (South Wales) Limited | Professional & scientific | 2010 |
| Hair & Beauty Supplies Ltd | Wholesale & retail | 2021 |
| Hair & Graces (IOW) Ltd | Other services | 2017 |
| Hair (UK) Limited | Other services | 2013 |
| Hair at Rage Limited | Other services | 2011 |
| Hair by Ceris Ltd | Other services | 2025 |
| Hair by Marketa Limited | Other services | 2025 |
| Hair Granted Limited | Other services | 2022 |
| Hair Lounge Newport IOW Limited | Other services | 2017 |
| HAIR@340 Ltd | Other services | 2024 |
| Hairbymorrisa Ltd | Wholesale & retail | 2025 |
| Hairleaders Limited | Other services | 2001 |
| Hairspray (Wales) Limited | Other services | 2011 |
| Hajech Limited | Health & social care | 2013 |
| Hajjsafe Limited | Manufacturing | 2011 |
| Haleema Property Services Ltd | Real estate | 2024 |
| Halfling Ltd | Information & communication | 2019 |
| Halfway Hotel (Cwmbran) Limited | Hospitality | 2022 |
| Halk Group Holdings Limited | Real estate | 2025 |
| Halk Holdings Limited | Real estate | 2025 |
| Hall 2 Hook Rigging Solutions Ltd | Other services | 2025 |
| Hall Enterprises Group Limited | Real estate | 2024 |
| Hallett Services Limited | Construction | 2026 |
| Hallmark Floors Limited | Construction | 2021 |
| Halls Blade Repairs Ltd | Manufacturing | 2021 |
| Halo Foods Limited | Manufacturing | 1989 |
| Hambly Court Management Ltd | Households | 2014 |
| Hamburger Creative Agency Limited | Other services | 2015 |
| Hamilton-Roberts Psychology Limited | Professional & scientific | 2023 |
| Hamkira Ltd | Wholesale & retail | 2022 |
| Hamlet Court Regeneration Ltd | Administrative & support | 2004 |
| Hammer Investment Properties Limited | Real estate | 2018 |
| Hammerspace Video Ltd | Information & communication | 2022 |
| Hammond Architectural Limited | Professional & scientific | 2002 |
| Hammond Development Consultancy Limited | Real estate | 2020 |
| Hampshire GAS Company Ltd | Construction | 2024 |
| Hampton Industrial Consulting Ltd | Administrative & support | 2023 |
| Hamstead Road Residents Ltd | Households | 2011 |
| Hamvay Transport Limited | Transport & logistics | 2017 |
| HAN Cars & Transports Ltd | Wholesale & retail | 2025 |
| HAN Transport Services Limited | Wholesale & retail | 2022 |
| Hanan (Newport) Ltd | Hospitality | 2017 |
| Handmade Mirror Designs Ltd | Manufacturing | 2018 |
| Handpost Hotel Limited | Hospitality | 2016 |
| Handpost Tandoori 18 Ltd | Hospitality | 2024 |
| Handspun Crafts Ltd | Manufacturing | 2022 |
| Handynest UK Limited | Wholesale & retail | 2025 |
| Hang Corporation Limited | Extraterritorial | 2021 |
| Hani and Reem Ltd | Real estate | 2023 |
| Hanman Marine Limited | Transport & logistics | 2012 |
| Hann Anderson Relocation Limited | Administrative & support | 2006 |
| Hannah Lowther Ltd | Arts & recreation | 2023 |
| Hanover Barn (Isle of Wight) Limited | Administrative & support | 1959 |
| Hanslip Asphalting Limited | Construction | 1987 |
| Happy Aero Ltd | Transport & logistics | 2019 |
| Happy Brothers Ltd | Wholesale & retail | 2024 |
| Happy Henry's Homes Limited | Manufacturing | 2021 |
| Happy Hive@Newport Limited | Health & social care | 2026 |
| Happy Hounds of Newport Ltd | Education | 2024 |
| Happy House (163) Ltd | Hospitality | 2019 |
| Happy Little Humans Ltd. | Education | 2024 |
| Happy Minds Learning Hub Ltd | Education | 2026 |
| Harbour FB Limited | Hospitality | 2016 |
| Harbour Pubs IW Limited | Hospitality | 2020 |
| Harco Holdings Ltd | Real estate | 2024 |
| Harcourt Trading & Investments Ltd | Real estate | 2018 |
| Hard Pressed Hifi Ltd | Wholesale & retail | 2022 |
| Hard Technical Solutions Ltd | Construction | 2025 |
| Hardacre I.T. Limited | Manufacturing | 2003 |
| Hardacre IT Property ( 2022 ) Ltd | Real estate | 2021 |
| Hardan Flooring Limited | Construction | 2021 |
| Hardee Travel Ltd | Administrative & support | 2025 |
| Harding Evans Legal Services Limited | Administrative & support | 2010 |
| Harding Evans Limited Liability Partnership | | 2005 |
| Harding Evans Services Limited | Administrative & support | 2004 |
| Hardings Holding Company Limited | Financial services | 2022 |
| Hardscaping Solutions Ltd | Construction | 2013 |
| Harkness ET AL. Limited | Wholesale & retail | 2024 |
| Harl Property Development Ltd | Real estate | 2021 |
| Harlech Commercial Finance Limited | Financial services | 2006 |
| Harlequin (NPT) Ltd | Hospitality | 2013 |
| Harlequin Business Consultants Limited | Information & communication | 2012 |
| Harlequin Healthcare Ltd | Wholesale & retail | 2018 |
| Harlow Car Group Limited | Wholesale & retail | 2021 |
| Harmony Limited Company Limited | Health & social care | 2013 |
| Harold & Franklin Ltd | Information & communication | 2011 |
| Haroon Iqbal Law Associates Limited | Professional & scientific | 2025 |
| Harper Adams Enterprises Limited | Administrative & support | 2009 |
| Harper Adams University | Education | 2012 |
| Harper Visuals Limited | Professional & scientific | 2018 |
| Harrington Financial Planning Ltd | Financial services | 2018 |
| Harrington Professional Services Limited | Information & communication | 2018 |
| Harris & Rowe (Commercials) Limited | Extraterritorial | 1985 |
| Harris & Rowe (Holdings) Limited | Real estate | 1993 |
| Harris Belting Limited | Manufacturing | 2016 |