| 01608353 Limited | | 1982 |
| 1 Team Energy Ltd | Professional & scientific | 2010 |
| 10 South Hill Park (Management) Limited | Households | 1998 |
| 101 Productions Limited | Information & communication | 2024 |
| 11 Avenue Road Management Limited | Households | 1993 |
| 1236 Promotions Limited | Arts & recreation | 2015 |
| 14 Carlisle Avenue (RTM) Co Limited | Households | 2012 |
| 16-19 Geescroft Walk RTM Company Limited | Administrative & support | 2010 |
| 19 Sports Ltd | Arts & recreation | 2024 |
| 19 Villa Road Flats (Luton) Management Company Limited | Real estate | 1986 |
| 19-40 Brooklands Court RTM Company Ltd | Households | 2018 |
| 1LR Solutions Ltd | Real estate | 2024 |
| 1ST Call Surveys Ltd | Energy | 2011 |
| 2 Bros BB Ltd | Other services | 2025 |
| 20 Sangora Road Limited | Households | 2003 |
| 20-FIFTEEN Sport Ltd | Professional & scientific | 2021 |
| 2012 Building Services Limited | Professional & scientific | 2017 |
| 2020 Cyber Investigations Limited | Administrative & support | 2020 |
| 2110 Consult Limited | Professional & scientific | 2009 |
| 2110 Consult Trustees Limited | Administrative & support | 2025 |
| 22 Twelve Ltd | Wholesale & retail | 2022 |
| 22-24 Q Street Investments Limited | Real estate | 2018 |
| 23 Financial Limited | Professional & scientific | 2015 |
| 24 Hour Pest Control Limited | Administrative & support | 2024 |
| 2468 Riverford Close Limited | Real estate | 2017 |
| 26 Hollybush Lane Limited | Households | 2019 |
| 266 Hatfield Road Limited | Professional & scientific | 2005 |
| 2COACH Executive Coaching Ltd | Professional & scientific | 2024 |
| 3 Kats Limited | Professional & scientific | 2017 |
| 350 Investment Partners LLP | | 2006 |
| 383 Commerce Ltd | Wholesale & retail | 2024 |
| 3H Property Consultants Limited | Real estate | 2008 |
| 3JS Consulting Limited | Professional & scientific | 2013 |
| 3MH Limited | Professional & scientific | 2021 |
| 3V3 UK Herts Ltd | Administrative & support | 2025 |
| 4 Sun Lane Management Company Ltd | Households | 2026 |
| 41 Crnet Ltd | Real estate | 2022 |
| 44/45 Cleveland Square Limited | Real estate | 1989 |
| 4G Associates Ltd | Professional & scientific | 2018 |
| 54 Bingham Road (Freehold) Company Limited | Households | 2008 |
| 56 Station Road Harpenden Residents' Association Limited | Households | 1976 |
| 5DAYS Digital Ltd | Professional & scientific | 2024 |
| 65 Codicote Road Developments Limited | Households | 2014 |
| 69 Christchurch Road Management Company Limited | Real estate | 2011 |
| 7 Legacy Property Solutions Ltd | Households | 2024 |
| 70 Kingsley Ltd | Real estate | 2021 |
| 7MM Holdings UK Ltd | Information & communication | 2025 |
| 86 Ballater Road Limited | Households | 2008 |
| 8TWENTY3 Limited | Wholesale & retail | 2016 |
| 96 Cazenove Road Management Company Limited | Households | 1997 |
| A & F Painting & Decorating Limited | Construction | 2003 |
| A Denny Partners Ltd | Professional & scientific | 2025 |
| A M Architecture Limited | Professional & scientific | 2008 |
| A M C Properties Limited | Real estate | 1999 |
| A Razaq Family Holdings Ltd | Real estate | 2026 |
| A Webster Consulting Ltd | Professional & scientific | 2022 |
| A. + D. Tyler Limited | Education | 1999 |
| A.C. HR Solutions Limited | Professional & scientific | 2013 |
| A.H Hairdressing Limited | Other services | 2022 |
| A.L.F. Office Solutions Ltd | Information & communication | 2006 |
| A.T.E Sales and Marketing Ltd | Professional & scientific | 2009 |
| A1Z Construction Limited | Construction | 2019 |
| A2Z Poster Limited | Wholesale & retail | 2024 |
| A3 IT Limited | Information & communication | 2010 |
| A40 Electrical Ltd | Construction | 2024 |
| Aagc Limited | Financial services | 2022 |
| Aaroc Limited | Real estate | 1975 |
| AB Property Portfolio Limited | Real estate | 2024 |
| AB Trading and Investing Ltd | Professional & scientific | 2013 |
| Abacus the Law C0STS Consultants Limited | Professional & scientific | 2008 |
| Abbot's Shoes Limited | Wholesale & retail | 2019 |
| Abby Goddard Ltd | Administrative & support | 2022 |
| Abcpay Ltd | Construction | 2015 |
| Abel Medical Ltd | Health & social care | 2013 |
| Abel Street Limited | Construction | 2019 |
| About Publishing Limited | Information & communication | 2001 |
| Abrey Private Clients LLP | | 2014 |
| Absolute Irrigation Ltd | Construction | 2024 |
| Abtbiz Consulting and Coaching Ltd | Professional & scientific | 2019 |
| Abydos Intelligent Solutions Limited | Information & communication | 2020 |
| AC Holiday Rentals Ltd | Administrative & support | 2013 |
| AC the Barber Limited | Other services | 2025 |
| Ac-Sqd Ltd | Construction | 2017 |
| Access Footage Limited | Arts & recreation | 2019 |
| ACG Construction and Refurbishment Limited | Construction | 2021 |
| ACG Markets Ltd | Financial services | 2022 |
| ACG Payments Limited | Financial services | 2026 |
| Acoustic Backs and Tracks Ltd | Wholesale & retail | 2024 |
| ACR Build Ltd | Construction | 2003 |
| Acre Invest (Collingdon) Limited | Construction | 2017 |
| Acre Invest Limited | Real estate | 2015 |
| Active 24/7 Plumbing Ltd | Construction | 2026 |
| ACTIVE4LESS Ltd | Professional & scientific | 2009 |
| Activetrainingworld Limited | Arts & recreation | 2011 |
| Actuare Limited | Information & communication | 1997 |
| ACX Engineering Consulting Ltd | Professional & scientific | 2021 |
| AD Performance Ltd | Wholesale & retail | 2023 |
| Adamantine Unlimited Ltd | Administrative & support | 2019 |
| Adamkern Ltd | Real estate | 2026 |
| Adatechnet Ltd | Wholesale & retail | 2021 |