| ADT Strategic Ltd | Professional & scientific | 2024 |
| Adtrafico LP | | 2016 |
| ADV Bill LP | | 2016 |
| ADV Production LP | | 2015 |
| Advan Home Ltd | Wholesale & retail | 2022 |
| Advance Alliance LP | | 2016 |
| Advance Angle LP | | 2015 |
| Advance Corporation L.P. | | 2010 |
| Advance Global Recruitment (Holdings) Limited | Administrative & support | 2014 |
| Advance Global Recruitment Ltd | Administrative & support | 2011 |
| Advance Inter LP | | 2011 |
| Advance Padel Ltd | Extraterritorial | 2021 |
| Advance Search and Selection Limited | Administrative & support | 2000 |
| Advance Work LP | | 2015 |
| Advanced Autos Limited | Wholesale & retail | 2008 |
| Advanced Body Therapies Ltd | Other services | 2025 |
| Advanced Circuit Integration ACI LP | | 2015 |
| Advanced Devops Solutions Limited | Administrative & support | 2016 |
| Advanced Digital Systems LP | | 2014 |
| Advanced Digital Technologies LP | | 2014 |
| Advanced Downhole Petrophysics Ltd | Administrative & support | 2012 |
| Advanced European Marketing & Co. | | 1993 |
| Advanced Integra LP | | 2015 |
| Advanced Piling Equipment Limited | Wholesale & retail | 2016 |
| Advanced Robotic Services Ltd. | Professional & scientific | 2021 |
| Advanced Roofing Edinburgh Limited | Construction | 2010 |
| Advanced Trading Services LP | | 2015 |
| Advanced Weather Applications Ltd. | Information & communication | 2009 |
| Advant Group LP | | 2016 |
| Advantage Coaching and Training Ltd | Professional & scientific | 2026 |
| Advantage Electrical Services Ltd | Construction | 2024 |
| Advantage Home Finance Ltd | Financial services | 2015 |
| Advantage HR Partners Limited | Administrative & support | 2026 |
| Advantage Learning Limited | Information & communication | 2003 |
| Advantage Sports Consultancy Ltd | Professional & scientific | 2017 |
| Advantica Solutions Ltd | Extraterritorial | 2018 |
| Advent LS II LP | | 2014 |
| Advent LS LP | | 2009 |
| Advent Management II Limited Partnership | | 1998 |
| Advent Management III Limited Partnership | | 2000 |
| Advent Management IV Limited Partnership | | 2004 |
| Advent Management Life Sciences Limited | Financial services | 2009 |
| Advent Management Limited Partnership | | 1988 |
| Adventis Consulting LP | | 2012 |
| Adventure Begins (Borders) Limited | Health & social care | 2024 |
| Adventure Business Solutions Scotland Limited | Professional & scientific | 2011 |
| Adventure Everything Ltd | Information & communication | 2019 |
| Adventurers Wanted Limited | Hospitality | 2025 |
| Adveq Real Assets Extracted Resources L.P. | | 2010 |
| Adveq Real Assets Green Power Resources L.P. | | 2010 |
| Adverstix LP | | 2016 |
| Advert Builder LP | | 2015 |
| Advertech LP | | 2015 |
| Advertising & Marketing Consultants & Co | | 1994 |
| Advertising Land LP | | 2016 |
| Advertising Platform LP | | 2024 |
| Advertision LP | | 2022 |
| Adviceworx Ltd | Professional & scientific | 2022 |
| Advicouns LP | | 2015 |
| Advie Properties Ltd | Construction | 2017 |
| Advino Group LP | | 2017 |
| Advise & Consult L.P. | | 2011 |
| Advisewatch Limited | Real estate | 1991 |
| Advisor Consult LP | | 2012 |
| Advisory Direct Limited | Information & communication | 2017 |
| Advocard | Other services | 2011 |
| Advocate's Close Limited | Hospitality | 2025 |
| Adwave LP | | 2018 |
| Adwoa Media Ltd | Information & communication | 2020 |
| Adworlds Technologies LP | | 2013 |
| ADX Sports Limited | Arts & recreation | 2017 |
| Adzz Ltd | Transport & logistics | 2020 |
| AE Edinburgh Nails Ltd | Other services | 2023 |
| AE Rope Tech Ltd | Construction | 2025 |
| AE3 C Sub-Feeder LP | | 2013 |
| AE5 SLP Alpha Energy 1 LP | | 2021 |
| AE5 SLP Alpha Energy 2 LP | | 2021 |
| AE5 SLP Alpha Energy 3 LP | | 2021 |
| AEB Heating Ltd | Construction | 2026 |
| AED Trans Group LP | | 2016 |
| Aedifico LP | | 2019 |
| AEF Electrical Ltd | Construction | 2013 |
| Aegis Fire Security and Electrical Ltd | Energy | 2020 |
| Aegis Property Care Limited | Construction | 1999 |
| Aegis Tributum Ltd | Professional & scientific | 2018 |
| Aegiss Limited | Information & communication | 2025 |
| Aegon Asset Management Limited | Financial services | 2000 |
| Aegon Asset Management UK Corporate Services Ltd | Administrative & support | 2026 |
| Aegon Asset Management UK Holdings Limited | Professional & scientific | 2009 |
| Aegon Asset Management UK PLC | Financial services | 1988 |
| Aegon EDC Limited | Administrative & support | 2009 |
| Aegon Investment Solutions - Nominee 1 (Gross) Ltd. | Administrative & support | 2011 |
| Aegon Investment Solutions - Nominee 2 (NET) Ltd. | Administrative & support | 2011 |
| Aegon Investment Solutions - Nominee 3 (ISA) Ltd. | Administrative & support | 2011 |
| Aegon Investment Solutions Ltd. | Administrative & support | 2011 |
| Aegon Sipp Nominee 2 Limited | Administrative & support | 2017 |
| Aegon Sipp Nominee Ltd | Administrative & support | 2011 |
| Aegon UK Corporate Services Limited | Administrative & support | 1996 |
| Aeif 1 Sponsor LP | | 2015 |
| Aeiffp LP | | 2009 |