| Greenflow Innovations Limited | Construction | 2025 |
| Greenheys Residents Group Limited | Households | 2003 |
| Greenleaf Northwood Limited | Hospitality | 2018 |
| Greenway Chesham Management Limited | Real estate | 2024 |
| Greenwich Builders & Consultants Ltd | Construction | 2022 |
| Grey Wolf Studios Limited | Professional & scientific | 2012 |
| Greyline Workforce Limited | Administrative & support | 2026 |
| Greywolf Graphics Limited | Manufacturing | 2019 |
| Groove Concierge Limited | Information & communication | 2013 |
| Group 5 Training Limited | Administrative & support | 1996 |
| Grove Dental Practice Limited | Health & social care | 2026 |
| Grove Dental Surgery Ltd | Health & social care | 2024 |
| Groveash Limited | Administrative & support | 2021 |
| Grovemile Associates Limited | Real estate | 2017 |
| Grow Businesses Limited | Professional & scientific | 2018 |
| Gsheth Home Limited | Real estate | 2019 |
| GSM Interiors & Contractors Ltd | Construction | 2018 |
| GT Spirit International Limited | Professional & scientific | 2022 |
| GTS Plant Limited | Administrative & support | 2008 |
| Gurleen Constructions Ltd | Construction | 2024 |
| Gwynne-Evans & Co Limited | Professional & scientific | 2012 |
| H Hills Ltd | Real estate | 2024 |
| H MIR Solutions Ltd | Information & communication | 2025 |
| H Rivers Ltd | Other services | 2024 |
| H&D Management Services Limited | Professional & scientific | 2015 |
| H-Labs Limited | Administrative & support | 2013 |
| H2 Aqua Precision Trade Limited | Construction | 2026 |
| H4 Aerospace (DE) Limited | Transport & logistics | 2006 |
| Hadyn Park Holdings Ltd | Hospitality | 2026 |
| Haev Design Limited | Construction | 2010 |
| Hair at Divine Ltd | Other services | 2014 |
| Half of Toto Ltd | Arts & recreation | 2014 |
| Halim Property Investment Limited | Real estate | 2017 |
| Hall Housing Ltd | Hospitality | 2018 |
| Hallowell Road Residents Association Limited | Construction | 1993 |
| Halls Health Limited | Arts & recreation | 2021 |
| Hamoon Limited | Hospitality | 2022 |
| Haneef Enterprises Limited | Real estate | 2019 |
| Hanger Bond Limited | Hospitality | 2012 |
| Hanlon & SON Paperhangers Limited | Construction | 2014 |
| Hanlon ASH Limited | Health & social care | 2010 |
| Hanlon Contractors Ltd | Construction | 2019 |
| Hanm London Limited | Financial services | 2026 |
| Hansom Property Company Limited | Real estate | 1962 |
| Hanza Properties Limited | Construction | 2006 |
| Happy Investing Ltd | Professional & scientific | 2022 |
| Happy Tree Academy Ltd | Education | 2015 |
| Harada Media Ltd | Information & communication | 2024 |
| Haran Brothers Limited | Professional & scientific | 2009 |
| Harbourplace Ltd | Wholesale & retail | 2003 |
| Hardcastle Burton Northwood Limited | Professional & scientific | 2025 |
| Haria Private Limited | Real estate | 2005 |
| Harringtons Builders Europe Limited | Construction | 2025 |
| Harringtons Contracting Limited | Construction | 2026 |
| Harrow Fresh Mart Limited | Wholesale & retail | 2026 |
| Harsons Limited | Real estate | 2009 |
| Hart Crossfit Limited | Arts & recreation | 2024 |
| Harvil Construction Company Limited | Construction | 2004 |
| Harvil Renovations Limited | Construction | 2022 |
| Hatton Textiles Limited | Wholesale & retail | 1998 |
| Hayes Estates Limited | Real estate | 2007 |
| Hayma Foods Limited | Hospitality | 2024 |
| Haymarket Consultancy Limited | Professional & scientific | 2024 |
| Hazy Investments LLP | | 2014 |
| Health and Vitality Bytes Ltd | Wholesale & retail | 2020 |
| Health Junkie Limited | Health & social care | 2012 |
| Heart Health U.K. Ltd | Health & social care | 2024 |
| Heathmere Limited | Households | 2015 |
| Hech Enterprises Ltd | Construction | 2016 |
| Hefs Newco a Limited | Real estate | 2019 |
| Hekima Consulting Limited | Professional & scientific | 2024 |
| Helia'Z Limited | Manufacturing | 2001 |
| Heliopolis Holdings Limited | Administrative & support | 2023 |
| Hellobobo Ltd | Real estate | 2023 |
| Hema Life Force Ltd | Professional & scientific | 2024 |
| Hemadri Chemicals UK Ltd | Wholesale & retail | 2026 |
| Hemant Singhal Limited | Health & social care | 2014 |
| Henry Taylor Limited | Transport & logistics | 2026 |
| Hens With Pens Ltd | Arts & recreation | 2020 |
| HER Integrative Clinic Limited | Health & social care | 2026 |
| Hera Communication Strategies Limited | Professional & scientific | 2019 |
| Hera Ventures Ltd | Real estate | 2024 |
| Herbal Vision Limited | Health & social care | 2024 |
| Herts & Herts Business Solutions Limited | Professional & scientific | 2012 |
| Herts Vehicle Sourcing Limited | Wholesale & retail | 2021 |
| Hestia Plutus Solicitors Limited | Professional & scientific | 2017 |
| Heuristic Care Limited | Financial services | 2025 |
| Hexa Living Limited | Real estate | 2023 |
| Hexa Properties Limited | Real estate | 2017 |
| Heyxio Ltd | Information & communication | 2026 |
| Hi-Fi Care Limited | Wholesale & retail | 1991 |
| Hibah Foods Limited | Hospitality | 2012 |
| High Herts Holding Ltd | Real estate | 2014 |
| High Links 5 Limited | Real estate | 2019 |
| High Pressure Hoses Limited | Wholesale & retail | 2025 |
| Highlife Health Limited | Health & social care | 2022 |
| Highlife Houses Limited | Households | 2023 |
| Hikma Harvest Co. Ltd | Wholesale & retail | 2025 |
| Hillbright Ltd | Real estate | 2017 |
| Hillingdon Print Ltd | Wholesale & retail | 2011 |