| British Green Energy Limited | High Wycombe | 2007 |
| Britned Development Limited | | 2001 |
| Brittanyia Renewable Energy Ltd | Blackpool | 2019 |
| Britton Court Energy Centre Limited | Norwich | 2022 |
| BRK 001 Limited | Manchester | 2018 |
| BRK 002 Limited | Exeter | 2018 |
| BRL Energy Ltd | Warrington | 2024 |
| Bro-Tathan Limited | Milton Keynes | 2024 |
| Broad Energy (Roden) Limited | Manchester | 2020 |
| Broad Lane Industrial Park Limited | Melksham | 2012 |
| Broad Oak Hydro Limited | Cumbria | 2012 |
| Broadcroft Consultants Ltd. | Bristol | 2016 |
| Broadfield and Company Limited | Carlisle | 2014 |
| Broadholm Energy Ltd | Girvan | 2022 |
| Broadholme Solar Farm Limited | Cheltenham | 2022 |
| Broadland Energy (Donich) Limited | Scarbrough | 2013 |
| Broadland Energy (Kiachnish) Limited | Scarbrough | 2013 |
| Broadland Energy (Laudale) Limited | Scarborough | 2013 |
| Broadland Energy (MOY) Limited | Scarbrough | 2013 |
| Broadland Power Solutions Ltd | Norwich | 2016 |
| Broadland Renewable Energy Limited | Scarborough | 2010 |
| Broadman Limited | Hull | 1990 |
| Broadshore Offshore Wind Farm Limited | Edinburgh | 2022 |
| Broadview Energy Developments Limited | London | 2005 |
| Broadview Energy Limited | London | 2003 |
| Broadway GAS Services Ltd | Ramsgate | 2011 |
| Brockagh Heights Renewables Limited | Londonderry | 2026 |
| Brockagh Wind Limited | Belfast | 2016 |
| Brockaghboy Windfarm Ltd | Belfast | 2007 |
| Brockhampton Solutions Limited | Havant | 2021 |
| Brockhill Solar Ltd | London | 2022 |
| Brockholes Community Energy Limited | London | 2017 |
| Brocklesby Biogas Ltd | London | 2016 |
| Brocklesby Energy Company Limited | Brocklesby | 2011 |
| Brockloch RIG I Limited | Glasgow | 1996 |
| Brockloch RIG Windfarm Limited | Glasgow | 1994 |
| Brockwell GAS Holdings Limited | Edinburgh | 2020 |
| Brockwell GAS Limited | Edinburgh | 2020 |
| Brockwell Storage & Solar Limited | London | 2015 |
| Brockwell Wind Developments Limited | Edinburgh | 2022 |
| Broken Scar Limited | London | 2021 |
| Bromborough Electric Forecourt Limited | Swindon | 2020 |
| Bromham Biogas Ltd | London | 2016 |
| Bromi GAS Heating Limited | Birmingham | 2019 |
| Brompton Climate Services Ltd | Doncaster | 2021 |
| Bromsgrove Power Limited | Stourbridge | 2022 |
| Bromview Limited | Bridgend | 2017 |
| Bron Coys Energy Storage Limited | Kings Langley | 2022 |
| Bron Fedw Hydro Scheme Limited | Pwllheli | 2005 |
| Bronllety Hydro Limited | Maidenhead | 2015 |
| Bronty Electrical Ltd | Pontefract | 2021 |
| Bronx Electrical Distributors Ltd | Birmingham | 2021 |
| Brook Contracting Solutions Limited | Lyndhurst | 2010 |
| Brook Green Innovations Limited | London | 2020 |
| Brook Green Supply Limited | London | 2015 |
| Brook Green Trading Limited | London | 2015 |
| Brook Hall Farm Solar Limited | Malmesbury | 2014 |
| Brook House IOW Services Limited | Newport | 2013 |
| Brookbarn Farm Solar Limited | London | 2014 |
| Brookdale Biogas (UK) Limited | Belfast | 2025 |
| Brooke Energy (Engineering) Limited | Cullompton | 2016 |
| Brooke Energy (Exeter) Limited | Cullompton | 2016 |
| Brooke Energy (Jewells) Limited | Cullompton | 2016 |
| Brooke Energy (Winchester) Limited | Cullompton | 2016 |
| Brooklands Altnagelvin NO.2 Limited | Magherafelt | 2015 |
| Brooklands and Sun Ltd | Worcester | 2024 |
| Brooklinn Hydro Limited | | 2006 |
| Brookside Solar Farm Limited | Reading | 2015 |
| Brookside Solar Limited | London | 2013 |
| Broomfield Electrical Services Trade Ltd | Gainsborough | 2020 |
| Broomfield Wind Ltd | Poole | 2013 |
| Browne Power Ltd | Strabane | 2011 |
| Brownhill Wind Farm Ltd | Huddersfield | 2022 |
| Browning Power Limited | London | 2011 |
| Brownlow Heat Transfer Limited | Craigavon | 2001 |
| Broxted Solar Co Ltd | London | 2012 |
| Bruach Caorainn Hydro Limited | Lochailort | 2015 |
| Bruachaig Hydro Limited | Edinburgh | 2014 |
| Brunel Heating & Plumbing Ltd | Luton | 2019 |
| Brunicon Ltd | Aldershot | 2023 |
| BRUNO919 Limited | Doncaster | 2017 |
| Brunt Hill Limited | Edinburgh | 2022 |
| Bruxiehill Wind Energy Limited | Aberdeen | 2008 |
| Brwe Ltd | Magherafelt | 2012 |
| Bryant Electrical Engineers Ltd | Redruth | 2008 |
| Brydon Electrical Limited | Cardiff | 2018 |
| Bryn Bachau Solar Farm Limited | London | 2015 |
| Bryn Gilwern Energy Park Limited | Cardiff | 2020 |
| Bryn Henllys SF Limited | London | 2012 |
| Bryn Power Limited | Hengoed | 2012 |
| Bryn Rhudd Energy Park Limited | Cardiff | 2021 |
| Bryn Y Gwynt Developments Limited | St. Asaph | 2013 |
| Bryn Y Gwynt Limited | St. Asaph | 2011 |
| Bryn YR Odyn Solar Developments Holdings Limited | London | 2014 |
| Bryn YR Odyn Solar Developments Limited | London | 2013 |
| Bryngolwg Energy Storage Limited | Reading | 2023 |
| Bryngolwg Solar Ltd | Cheltenham | 2022 |
| Bryngwyn Energy Park Limited | Cardiff | 2021 |
| Brynteg Solar Limited | London | 2013 |
| Brynwell Farm Solar Limited | Liverpool | 2020 |