| Abbots ANN Farm Solar Park Limited | Gatwick | 2012 |
| Abbots Ripton Solar Energy Holding Limited | London | 2011 |
| Abbots Ripton Solar Energy Limited | London | 2013 |
| ABC Air Conditioning Limited | London | 2017 |
| ABC Refrigeration Supplies Limited | Harrow | 2026 |
| ABC Wind Ltd | Aberdeen | 2012 |
| Abdul Electricals Ltd | Slough | 2025 |
| Abei Energy Green I Limited | Bristol | 2021 |
| Abei Energy Green II Limited | Bristol | 2021 |
| Abei Energy Green III Limited | Bristol | 2021 |
| Abei Energy Green IV Limited | Bristol | 2021 |
| Abei Energy Green IX Ltd | Bristol | 2022 |
| Abei Energy Green V Limited | Bristol | 2021 |
| Abei Energy Green VI Limited | Bristol | 2022 |
| Abei Energy Green VII Ltd | Bristol | 2022 |
| Abei Energy Green Viii Ltd | Bristol | 2022 |
| Abei Energy Green X Ltd | Bristol | 2022 |
| Abei Energy Limited | Bristol | 2019 |
| Abel Air Conditioning Limited | Welling | 2014 |
| Abel Utilities Ltd | Bolton | 2024 |
| Abengoa Concessions Investments Limited | Reading | 2013 |
| Aberarder Wind Farm (Scotland) Limited | Perth | 2022 |
| Abercomyn Solar Limited | London | 2013 |
| Abercorn Generation Limited | Greenock | 2018 |
| Aberdeen Heat and Power Company Limited | Edinburgh | 2002 |
| Aberdeen Mechanical Services Limited | Aberdeen | 2020 |
| Aberdeen Offshore Wind Farm Limited | Edinburgh | 2005 |
| Aberedw Energy Park Limited | Cardiff | 2020 |
| Abergelli Farm Bess Limited | Cheltenham | 2022 |
| Abergelli Solar Limited | London | 2011 |
| Abergwaun Community Turbines Limited | Haverfordwest | 2014 |
| Abernethy Developments Limited | Nethy Bridge | 2011 |
| Abersanda Limited | Nethy Bridge | 2011 |
| Aberthaw Green Limited | London | 2020 |
| Abhainn Dubh Limited | Edinburgh | 2022 |
| Abham Storage Limited | London | 2017 |
| Abingdon Air Conditioning Services Limited | Abingdon | 2005 |
| ABL Consultants Motherwell Ltd | Motherwell | 2022 |
| Able GAS Heating Ltd | Manchester | 2016 |
| ABM Electrical Services Ltd | Snodland | 2021 |
| ABM Electrics Ltd | London | 2017 |
| Abode Heating Ltd | Ruislip | 2020 |
| ABP Renewables Ltd | Gateshead | 2025 |
| Abriachan Electric Company Limited | London | 2015 |
| Abronia Energy Limited | London | 2017 |
| ABS Building Services Ltd | Bootle | 2020 |
| ABS Electrical Services Ltd | Birmingham | 2023 |
| ABS Speedtrans UK Ltd | Birmingham | 2007 |
| Absolute Building Control Limited | Uxbridge | 2013 |
| Absolute Climate Solutions Ltd | Witney | 2016 |
| Absolute Cooling Ltd | Glasgow | 2025 |
| Absolute Eco Energy Ltd | Dartford | 2009 |
| Absolute Electrical Services (Scotland) Ltd | Longniddry | 2014 |
| Absolute GAS Services (Scotland) Ltd | Glasgow | 2013 |
| ABT U.K. International Corporation Limited | London | 2016 |
| AC @ Home Limited | Bingley | 2021 |
| AC and Heating Needs.Com Ltd | 20/20 Business Park | 2019 |
| AC and Vent Solutions Limited | Manchester | 2022 |
| AC Breeze Limited | Staines | 2010 |
| AC Building Services Limited | Birmingham | 2014 |
| AC Chillmaster Ltd | Bishop'S Stortford | 2024 |
| AC Compressors Limited | Reading | 2014 |
| AC Electrical Consulting Services Limited | Chelmsford | 2017 |
| AC Electrical Services 09 Ltd | London | 2009 |
| AC Global Services Ltd | Shoreham-By-Sea | 2019 |
| AC Solutions and Services Ltd | Rochester | 2022 |
| AC Wind Power Ltd | Craigavon | 2012 |
| Acacia Spring Properties Ltd | Birmingham | 2025 |
| ACC Renewable Energy Ltd | Aintree | 2020 |
| Accelerate Energy Holdings Limited | Belfast | 2023 |
| Access Install Limited | Barnsley | 2015 |
| Access.Energy Limited | Edinburgh | 2019 |
| Accessible Mobility Africa CIC | Northampton | 2026 |
| Accfm Limited | Aylesbury | 2003 |
| Accretion Energies Limited | London | 2019 |
| Accrue Energy Ltd | Bury | 2024 |
| Accurate Air-Conditioning Limited | London | 2007 |
| Accuro Acbs Limited | Stevenage | 2006 |
| Acdc London Electrical Ltd | Barking | 2018 |
| Ace Control Systems Limited | Newry | 2006 |
| Ace Green Energy UK Ltd | Colchester | 2021 |
| Ace Group Solution Ltd | London | 2025 |
| Ace Heating & Cooling Services Ltd | Colchester | 2019 |
| Ace Instruments Ltd | Ruislip, | 2025 |
| Ace Maintenance (Air Conditioning) Limited | Brentwood | 2024 |
| Ace Mechanical Services Limited | Acccrington | 2018 |
| Aceon Energy Ltd | Telford | 2020 |
| Achairn Energy Limited | Edinburgh | 2006 |
| Achanalt Bess Limited | Newcastle Upon Tyne | 2023 |
| Acharn Hydro Limited | Perthshirte | 1992 |
| Achillies Training Ltd | Wisbech | 2025 |
| Achnacarry Hydro Ltd | Edinburgh | 2009 |
| Achnacreebeag Energy Limited | Oban | 2010 |
| Achterneed Hydro Scheme Ltd. | Dingwall | 2014 |
| ACJ Air Conditioning & Heating Ltd | Stroud | 2020 |
| Ackron Wind Farm Ltd | Glasgow | 2014 |
| Aclp Solar Limited | Portsmouth | 2025 |
| ACM (Asset Management) Limited | Norwich | 2023 |
| ACM Renewable Solutions Ltd | Houghton Le Spring | 2026 |
| ACN Plumbing & Heating Ltd | St. Albans | 2012 |