| Hedge Space CIC | Agriculture & fishing | 2023 |
| Heley International Limited | Wholesale & retail | 1976 |
| Hephzibah Investment Limited | Real estate | 2021 |
| HER Data Limited | Information & communication | 2017 |
| Herd Hire Rayleigh Limited | Administrative & support | 2022 |
| Herd Rayleigh Remarketing Limited | Wholesale & retail | 2024 |
| Heron Automotive Limited | Wholesale & retail | 2023 |
| Heron Stream Place Management Company Ltd | Households | 2012 |
| Hezekiah Consulting Limited | Construction | 2016 |
| HGK Design & Build Limited | Construction | 2016 |
| Hiburban Limited | Administrative & support | 2023 |
| Hickey's D.I.Y & Motor Centre Limited | Wholesale & retail | 2012 |
| Hickling Properties Limited | Real estate | 1986 |
| Highlite Techniques Limited | Administrative & support | 1988 |
| Hill Building Group Ltd | Construction | 2025 |
| Hilmi Ltd | Wholesale & retail | 2019 |
| Hire a Hubby Chelmsford Limited | Construction | 2015 |
| HK 217 Limited | Hospitality | 2024 |
| HL Urban Limited | Households | 2023 |
| Hmac Ventilation Services LLP | | 2014 |
| Hoard Point Limited | Real estate | 2024 |
| Hockley Angling Club Limited | Agriculture & fishing | 2025 |
| Hockley Electrical Contractors Limited | Construction | 2018 |
| Hockley Massage Ltd | Other services | 2025 |
| Holly Court RTM Company Limited | Households | 2019 |
| Holly Goodchild Ltd | Professional & scientific | 2022 |
| Hollywood Driving Services Ltd | Transport & logistics | 2010 |
| Home & Mind Essentials Ltd | Wholesale & retail | 2024 |
| Home Legal Direct Ltd | Administrative & support | 2017 |
| Homes & Watson Ltd | Construction | 2019 |
| Homes by Haywards Ltd | Hospitality | 2023 |
| Honest Builders Group Limited | Real estate | 2026 |
| Honeyz Tanning Limited | Arts & recreation | 2024 |
| Hope Restored Ltd | Health & social care | 2016 |
| Hopeworx | Wholesale & retail | 2012 |
| Hopkins Young Electrical Trustee Limited | Extraterritorial | 2025 |
| Horizon Vista LLP | | 2022 |
| HPC Blue Limited | Financial services | 2014 |
| HR Trading Consultancy Ltd | Financial services | 2025 |
| HRH Complete Building Services Limited | Construction | 2010 |
| Hubfind Limited | Professional & scientific | 2016 |
| Hudson Creative Services Ltd | Professional & scientific | 2025 |
| Humans London Limited | Administrative & support | 2019 |
| Hummingbirds Services Limited | Professional & scientific | 2021 |
| Hungry Boys Dining Ltd | Hospitality | 2021 |
| Hunters Glass Limited | Construction | 2018 |
| Hvac Project Services Ltd | Construction | 2025 |
| Hybrid Risk Management Limited | Financial services | 2025 |
| Hydro Drains Limited | Construction | 2000 |
| Hydro-Care Environmental Limited | Water & waste | 2012 |
| Hydrotech Detailing Ltd | Wholesale & retail | 2026 |
| I CAN Write Your PAY Cheque Limited | Financial services | 2018 |
| I Move 4 U . COM Limited | Other services | 2005 |
| I S Utilities Limited | Construction | 2018 |
| I.P Operations Ltd | Construction | 2017 |
| I.T. Training (Gants Hill) Limited | Information & communication | 2001 |
| IAN Tinsley & Co Ltd | Real estate | 2020 |
| Icanplan LHR Limited | Construction | 2009 |
| Iceni Driving School Ltd | Education | 2025 |
| ICM Fire Limited | Construction | 2000 |
| ICM Plumbing and GAS Maintenance Ltd | Construction | 2016 |
| Icomedge Ltd | Information & communication | 2014 |
| Identity Fitness Ltd | Arts & recreation | 2011 |
| Idet Ltd | Financial services | 2024 |
| Igbsolutions Limited | Professional & scientific | 2016 |
| Iiksir Development Ltd | Other services | 2020 |
| Ijust Evolution Limited | Construction | 2019 |
| Imac GAS Services Ltd | Construction | 2017 |
| Imogen Davis Interiors Ltd | Professional & scientific | 2025 |
| Impact Place, Space and Social Value Ltd | Professional & scientific | 2024 |
| Imperial Park Motor Co. Ltd | Wholesale & retail | 2005 |
| Imperium Mechanical and Electrical Limited | Construction | 2022 |
| Independent Adjudication Services Limited | Other services | 2016 |
| Independent Social Care Solutions Ltd | Health & social care | 2012 |
| Indigo Compliance Consulting Limited | Financial services | 2016 |
| Infinite PPF Limited | Wholesale & retail | 2025 |
| Infinity Addiction Services Ltd | Health & social care | 2025 |
| Infinity Addiction Solutions Ltd | Health & social care | 2019 |
| Ingenious Essentials Limited | Wholesale & retail | 2024 |
| Inmeres Solutions Limited | Information & communication | 2001 |
| Innercore Renewables Ltd | Construction | 2023 |
| Innercore Services Ltd | Construction | 2019 |
| Inprints T-Shirts Limited | Wholesale & retail | 2013 |
| Inspire Freeholds Limited | Real estate | 2017 |
| Inspired Practice Southampton Limited | Health & social care | 2014 |
| Inspired ZEN Solutions Limited | Manufacturing | 2022 |
| Insurance Complaints Bureau Limited | Financial services | 2009 |
| Intelligence Projects Ltd | Professional & scientific | 2026 |
| Intelligent Physio Limited | Health & social care | 2025 |
| Interior and Construction Limited | Construction | 2010 |
| Interlink Alloy Systems Limited | Manufacturing | 1987 |
| International Sporting Solutions Limited | Other services | 2016 |
| Intex Design Limited | Professional & scientific | 2009 |
| Invertendo Ltd | Health & social care | 2014 |
| Investments and Pensions Limited | Financial services | 2017 |
| Ipatch Ltd | Construction | 2020 |
| Iplumb London Services Limited | Construction | 2022 |
| Island Contract Cleaning Limited | Hospitality | 2006 |
| Istaff Healthcare LLP | | 2016 |
| Itheart Limited | Information & communication | 2017 |