| Afentra (Angola) Ltd | London | 2022 |
| Afentra (Offshore Developments) Ltd | London | 2024 |
| Afentra (Onshore Developments) Ltd | London | 2014 |
| Afentra (UK) Ltd | London | 2000 |
| Afentra PLC | London | 1983 |
| Afraid Knot Ltd | Inverurie | 2024 |
| Afrex Solutions Ltd | London | 2024 |
| Africa Minerals and Miners Centre Ltd | Ruislip | 2023 |
| Africa Mining and Licencing Company UK Ltd | London | 2023 |
| Africa Power Operations Limited | Camberley | 2013 |
| Africa Resources Co. Ltd | London | 2019 |
| African Copper Investments Ltd | London | 2025 |
| African Diamonds Limited | London | 2000 |
| African Energy Equity Resources Limited | London | 2006 |
| African Gold Mines (Uganda) Limited | Barrow-In-Furness | 2015 |
| African Gold Mines Limited | Barrow-In-Furness | 2014 |
| African Great Lakes Investments Limited | London | 2020 |
| African Minerals Engineering Limited | Birmingham | 2009 |
| Africastones Limited | London | 2025 |
| Afrik Mining Consultants Limited | Truro | 2026 |
| Afriresourses Limited | Houghton Le Spring | 2023 |
| Afrix Freight Logistics and Holding Limited | Croydon | 2022 |
| Afrock International Ltd | Stanmore | 2023 |
| AG OIL Ltd | Billericay | 2021 |
| AG Paving and Building Products Limited | Fivemiletown | 1960 |
| AG Procurement Services Ltd | Ellon | 2018 |
| AGA Mining Ltd | London | 2025 |
| AGB Contracting Ltd | Longforgan | 2018 |
| Agency OIL Ltd | Addlestone | 2018 |
| AGG Well Services Ltd | Montrose | 2014 |
| Aggbag Limited | Nuneaton | 2000 |
| Aggregate Processing Solutions Limited | Bristol | 2004 |
| Aggregate Recycling (UK) Limited | Pocklington York | 2000 |
| Aggregate Technology Limited | Laurencekirk | 2017 |
| Aggregates and Minerals Limited | Leicester | 1965 |
| Aggregates Express Quarry Products & Recycling (Forest Wood) Ltd | Rhondda Cynon Taff | 2022 |
| Aggregates Express Quarry Products Ltd | Rhondda Cynon Taff | 2021 |
| Aggregates Supplies and Recycling Ltd | London | 2024 |
| Aggregates West Limited | Plympton | 2020 |
| Aggrex Limited | Brigg | 2026 |
| Aggrilime Supplies Ltd | Alresford | 2025 |
| Aggserve Ltd | Kenilworth | 2020 |
| AGL Steelform Ltd | Colchester | 2009 |
| Agora OIL and GAS (UK) Limited | Edinburgh | 2009 |
| AGR (Aberdeen) Limited | Aberdeen | 2011 |
| Agraal Ltd | London | 2025 |
| Agrocanturk Tarim Kimya DIS Ticaret Ltd | Cambridge | 2026 |
| AGW Mechanical Services Limited | Blyth | 2023 |
| AGW OIL & GAS Ltd | Northampton | 2017 |
| AH Impact Piling Services Ltd | Great Yarmouth | 2021 |
| Ahana Energy Ltd | London | 2026 |
| Ahead SCM Limited | Aberdeen | 2011 |
| Ahern Land Reclamation Limited | Woodford Green | 1982 |
| AI Business Services Consulting Ltd | London | 2021 |
| Aiah Ltd | Middlesbrough | 2025 |
| AIM Group Industry Limited | London | 2024 |
| AIM Measurement Services Ltd | Aylesbury | 2017 |
| Airborne Geoscience Solutions Limited | London | 2017 |
| Aircross Express Investments Ltd | Basildon | 2025 |
| Aislaby Stone Limited | Whitby | 2002 |
| AJ Well Services Ltd | Aberdeen | 2010 |
| AJ WSS Ltd | Montrose | 2017 |
| Ajax Resources PLC | London | 2021 |
| AJC Aggregates Limited | Rotherham | 2007 |
| AJC OIL & GAS Consulting Ltd | Buckie | 2017 |
| AJG Subsea Services Ltd | Isle Of Lewis | 2019 |
| AJH Pipefitting Solutions Ltd | Middlesbrough | 2017 |
| AJK Project Services Ltd | Glasgow | 2014 |
| AJL Consultancy Limited | Aberdare | 2021 |
| AJL Engineering Ltd | Billingham | 2026 |
| AJL Process Consultants Limited | Brechin | 2018 |
| AJM Inspection Services Ltd | Aberdeen | 2017 |
| Ajmining Ltd | Bridport | 2020 |
| Ajobi Integrated International Group Limited | Romford | 2025 |
| AJP Offshore Limited | Liverpool | 2019 |
| AJP Piping Limited | Kilmacolm | 2017 |
| AK OIL & GAS Global Ltd | London | 2024 |
| AK Process and Project Engineering Ltd | Nuneaton | 2021 |
| AK Westside PLK Limited | Whitby | 2013 |
| AKA Energy Limited | Sudbury | 2025 |
| Akarana Limited | Cambridge | 1997 |
| Aker BP UK Limited | London | 2020 |
| AKH Inspection Services Limited | Fleetwood | 2017 |
| Akporotu Properties Services (UK) Ltd | London | 2015 |
| AKS Services Group Limited | Watford | 2017 |
| Aksm Montrose Ltd | Montrose | 2018 |
| Aktobe Holdings Ltd | Spalding | 2022 |
| Akureum Ltd | London | 2022 |
| AL HAJ Pakistan Exploration Limited | Uxbridge | 1974 |
| AL Hatimy Trading Limited | Bedford | 2019 |
| AL Murray Services Ltd | Brechin | 2017 |
| AL Qudra Drilling Company Limited | Aberdeen | 2017 |
| AL Shumookh UK Company for OIL & Energy Services Ltd | Enfield | 2024 |
| AL Tatweer Ltd | London | 2021 |
| Al-Busttan UK Limited | Leighton Buzzard | 2016 |
| Al-Sanad Ltd | Salisbury | 2024 |
| Alan Herbert Ltd | Whitby | 2012 |
| Alan M Ross (Sand & Gravel) Limited | Muir Of Ord | 2013 |
| Alan Train Limited | Bishopbriggs | 2008 |
| Alan Watt Enterprises Ltd | Elgin | 2019 |