| Garden House Hospice Trading Limited | Wholesale & retail | 1991 |
| Gendi Limited | Health & social care | 2002 |
| Gene Digital Ltd. | Professional & scientific | 2019 |
| Gogo Green Organics Ltd | Health & social care | 2019 |
| Green Willow Textile London Ltd | Manufacturing | 2020 |
| Greenways Estate Services Ltd | Administrative & support | 2021 |
| Growthscope Ltd | Professional & scientific | 2017 |
| H & W Property Valuers Limited | Construction | 2021 |
| Harps Teamwear Ltd | Manufacturing | 2018 |
| Hart AI Consulting Ltd | Information & communication | 2023 |
| Hawksure Holdings Limited | Real estate | 2014 |
| Heathco Ltd | Wholesale & retail | 2010 |
| Helmet Integrated Systems Limited | Manufacturing | 1992 |
| Hertfordshire Independent Living Service Limited | Hospitality | 2015 |
| Hertfordshire Storage Solutions Limited | Transport & logistics | 2017 |
| Heyland & Whittle Soap and Herbal Merchants Limited | Manufacturing | 2025 |
| Hitchin Lodge 6561 DMF | Other services | 2009 |
| Hobby and YOU Limited | Wholesale & retail | 2013 |
| HSC Security Limited | Administrative & support | 2017 |
| Hslc Ltd | Administrative & support | 2025 |
| Hyno Medics Ltd | Health & social care | 2026 |
| Icknield Garage(Letchworth)Limited | Wholesale & retail | 1959 |
| Idnet Limited | Information & communication | 1999 |
| IGB Fencing Limited | Construction | 2012 |
| Imhotep Medica Ltd | Health & social care | 2025 |
| Industrial Electronic Repairs Ltd | Manufacturing | 2003 |
| Infinity Developments Limited | Information & communication | 1995 |
| Inspiration to Art Ltd | Wholesale & retail | 2016 |
| Itechnicalauthor Ltd | Professional & scientific | 2012 |
| J M Hill Limited | Professional & scientific | 2025 |
| Jabbercoms Limited | Information & communication | 2014 |
| JAC Locums Limited | Information & communication | 2012 |
| Jameson Legal Group Limited | Administrative & support | 2015 |
| Jeval Limited | Financial services | 2002 |
| Jjhh Limited | Arts & recreation | 2019 |
| Jmac Rigging Limited | Construction | 2022 |
| JO Cares Company Ltd | Health & social care | 2021 |
| JSS Mortgage Management Limited | Financial services | 2016 |
| Jubilee Social LLP | | 2017 |
| K W Maintenance Limited | Administrative & support | 2024 |
| Kaaripa Consulting Limited | Professional & scientific | 2009 |
| Kaaripa Property Group Limited | Real estate | 2015 |
| Kattz (YH) Ltd | Real estate | 2019 |
| Kattz Group Limited | Financial services | 2018 |
| Kenneth Turner Limited | Wholesale & retail | 2025 |
| Kleinations Ltd | Wholesale & retail | 2024 |
| LA Lucia Ltd | Transport & logistics | 2011 |
| LA Recycling Limited | Information & communication | 2018 |
| Lane & Bennetts Ltd | Real estate | 2011 |
| Lavender Print Ltd | Administrative & support | 2017 |
| Lawrence Cloisters Trust Limited | Other services | 1949 |
| Leather Lane Foods Ltd | Wholesale & retail | 2019 |
| Letchworth Coachworks Limited | Wholesale & retail | 2012 |
| Letchworth Eyecare Limited | Wholesale & retail | 2012 |
| Letchworth Pizza Pasta Limited | Hospitality | 2016 |
| Letchworth Steel Limited | Manufacturing | 1988 |
| Levant Retail Brent Cross Ltd | Wholesale & retail | 2019 |
| Level PAR Ltd | Arts & recreation | 2021 |
| Leysbrook Limited | Real estate | 2018 |
| Liliana Beauty Ltd | Wholesale & retail | 2023 |
| Lisen Ltd | Professional & scientific | 2025 |
| Lloyds Marine & Leisure Supplies Limited | Wholesale & retail | 2021 |
| LPS (Leathem Plant Solutions) Ltd | Transport & logistics | 2012 |
| Lytton Financial Limited | Financial services | 2019 |
| M P Building Limited | Construction | 2004 |
| M&E Investment Properties Ltd | Real estate | 2020 |
| M. K. Properties Stevenage Limited | Real estate | 2022 |
| M. S. Research Treatment and Education Limited | Health & social care | 1994 |
| M.E.T Properties Limited | Real estate | 2020 |
| MAD About Coffee Limited | Hospitality | 2006 |
| Magical Bytes Ltd | Information & communication | 2016 |
| Mallon Hind Holdings Limited | Professional & scientific | 2010 |
| Mallon Hind Homes Ltd | Real estate | 2006 |
| Mallon Hind Properties Limited | Real estate | 2017 |
| Market Metals Limited | Wholesale & retail | 1972 |
| Marlex Marine Technology Limited | Professional & scientific | 2007 |
| Marliz Investments Limited | Real estate | 1960 |
| Mase Group Limited | Real estate | 2018 |
| Matam Living Ltd | Real estate | 2024 |
| Matam Residential Ltd | Real estate | 2025 |
| Maxsmibury Properties Ltd | Construction | 2006 |
| Mayfair Trading & Investments Limited | Administrative & support | 2020 |
| MBR Process Design Limited | Construction | 2004 |
| Meridian House Baldock Limited | Real estate | 2023 |
| MFD Funeral Consultants Ltd | Other services | 2023 |
| Millgar Engineering Ltd | Professional & scientific | 2003 |
| Mivus Limited | Professional & scientific | 2016 |
| Mobility World Limited | Wholesale & retail | 1994 |
| Momentum Y Ltd | Real estate | 2023 |
| Moss'B'Gone Limited | Construction | 2019 |
| Mrcl Tech Ltd | Information & communication | 2020 |
| Muddy Dog Care Ltd | Agriculture & fishing | 2024 |
| Multiple Sclerosis Trust | Health & social care | 2001 |
| Nawa Food Ltd | Wholesale & retail | 2023 |
| Nawa Kitchen Limited | Hospitality | 2013 |
| Nawa Kitchen London Ltd | Wholesale & retail | 2016 |
| NET Results (Online Marketing) Limited | Professional & scientific | 2012 |
| Neurovista Health Ltd | Health & social care | 2025 |
| New Compass Limited | Professional & scientific | 2024 |
| New Holland Investments Limited | Manufacturing | 2024 |