| A.Shiro Ltd | Other services | 2026 |
| A.T.F. Electrical Contractors Ltd | Construction | 2005 |
| A.V. (Uckfield) Limited | Real estate | 1956 |
| A.V. Barwick Limited | Real estate | 1965 |
| A.W. Clinics Limited | Health & social care | 2010 |
| A1 Dents Limited | Wholesale & retail | 2000 |
| A1 Glass & Glazing (Brighton) Limited | Construction | 2008 |
| A1 Sparkles Limited | Wholesale & retail | 2017 |
| A1 Tour Operator Ltd | Administrative & support | 2023 |
| A17 Group Ltd | Construction | 2024 |
| A2Z Study Abroad Ltd | Professional & scientific | 2024 |
| A8 Learning Ltd | Education | 2025 |
| AA Capital Services Ltd | Wholesale & retail | 2024 |
| AA Safe Security Ltd | Administrative & support | 2025 |
| AAB (Silverdale) Limited | Households | 1997 |
| AAD Property Solutions Ltd | Real estate | 2018 |
| AAE Fast Food Limited | Hospitality | 2022 |
| Aahil Property Ltd | Real estate | 2026 |
| AAM Hospitality & Leisure Group Ltd | Hospitality | 2024 |
| AAO Consulting Limited | Professional & scientific | 2024 |
| Aariyatech UK Limited | Information & communication | 2025 |
| Aarondile Limited | Households | 1989 |
| Aartee Bright Bar Limited | Manufacturing | 1999 |
| Aartee Bright Bar Property Limited | Real estate | 2010 |
| Aartee Steel Group Limited | Manufacturing | 2010 |
| Aartee Steel Holdings Limited | Professional & scientific | 2013 |
| Aartee Steel Operations Limited | Professional & scientific | 2010 |
| AB Camere Ltd | Real estate | 2022 |
| AB Drive Solution Limited | Wholesale & retail | 2025 |
| AB Impact Ltd | Professional & scientific | 2025 |
| AB Trading (Sussex) Limited | Wholesale & retail | 2013 |
| ABA VIZ Ltd | Wholesale & retail | 2026 |
| Abaci Fitness Ltd | Arts & recreation | 2021 |
| Abacus Industrial Flooring Ltd | Administrative & support | 2008 |
| Abalone Consulting Ltd | Professional & scientific | 2018 |
| Abandofbrothers | Education | 2007 |
| Abatsamara Limited | Information & communication | 2025 |
| Abbadigroup Ltd | Real estate | 2022 |
| Abbingsworth Properties Limited | Real estate | 2010 |
| ABC Autos Ltd | Wholesale & retail | 2019 |
| ABC Dental Surgery Ltd | Health & social care | 2013 |
| ABC Translations Ltd | Professional & scientific | 2006 |
| Abdin Developments Ltd | Extraterritorial | 2023 |
| Abel Ag-Tech Limited | Administrative & support | 1983 |
| Abelia Management Ltd | Real estate | 1998 |
| Aberdeen Seafood Brighton Limited | Hospitality | 2025 |
| ABI Enterprises Ltd | Real estate | 2016 |
| Abie's Food Mart Limited | Wholesale & retail | 2025 |
| Abies Essentials Limited | Wholesale & retail | 2025 |
| Abmm Properties Limited | Real estate | 2019 |
| Abob Trading Ltd | Health & social care | 2015 |
| Abode Home & Gifts Ltd | Wholesale & retail | 2024 |
| Abode Living Limited | Wholesale & retail | 2007 |
| Abodehero Limited | Real estate | 2022 |
| Aborealis Limited | Health & social care | 2019 |
| About Balance Ltd | Health & social care | 2017 |
| Above ALL Cards Ltd | Wholesale & retail | 2026 |
| Abrams Consulting Limited | Professional & scientific | 2024 |
| Abraxor Ltd | Information & communication | 2006 |
| ABS Electrical Supplies Limited | Wholesale & retail | 2009 |
| ABS Property Maintenance Limited | Construction | 2011 |
| Absolute Arabic Ltd | Professional & scientific | 2023 |
| Absolute Forward Ltd | Professional & scientific | 2024 |
| Abstractsys Limited | Information & communication | 2013 |
| Abtec Nexus Bidco Limited | Financial services | 2025 |
| Abtec Nexus Topco Limited | Financial services | 2025 |
| Abundare Limited | Health & social care | 2017 |
| Abyssinia Brighton Ltd | Hospitality | 2026 |
| AC Plumbers Ltd | Construction | 2016 |
| AC Prop Limited | Real estate | 2015 |
| AC Tax Services Limited | Professional & scientific | 2003 |
| Academy Music Management Limited | Information & communication | 2007 |
| Acadia Bidco Limited | Financial services | 2025 |
| Acadia Midco Limited | Financial services | 2025 |
| Acadia Topco Limited | Financial services | 2025 |
| Acai Guara Boost Food & Beverages Ltd | Wholesale & retail | 2025 |
| ACB Actual Customer Behaviour LLP | | 2005 |
| Acbl Ltd | Construction | 2021 |
| Accel Consulting Limited | Construction | 2002 |
| Accent Design Limited | Professional & scientific | 2025 |
| Accentia Management Services Limited | Professional & scientific | 2011 |
| Accordance Technical Services Ltd | Professional & scientific | 2007 |
| Account Management NOW Ltd | Administrative & support | 2015 |
| Accountaholic Brighton Ltd | Professional & scientific | 2008 |
| Accountancy & Management Limited | Professional & scientific | 2007 |
| Accountancy 360 Ltd | Professional & scientific | 2020 |
| Accountancy Connections Ltd | Extraterritorial | 2011 |
| Accounting & Business Solutions Ltd. | Professional & scientific | 2025 |
| Accrue Property Limited | Real estate | 2016 |
| Acct Investments Limited | Real estate | 2023 |
| Acctsourcr Ltd | Professional & scientific | 2021 |
| Accurate Background UK Limited | Administrative & support | 2019 |
| Accurate Ceilings & Interiors Ltd | Construction | 2019 |
| Accurate DIE Cast Limited | Wholesale & retail | 1996 |
| Accurate Marketing Limited | Professional & scientific | 2006 |
| Accurate Property Page Limited | Real estate | 2024 |
| Accurate Roofing & Building Limited | Construction | 2015 |
| Accuweb Holding Ltd | Financial services | 2021 |
| Ace and More Properties Ltd | Real estate | 2026 |
| Ace and More Technology Ltd | Information & communication | 2023 |