| Arab Social Media Federation | London | 2022 |
| Arabella Moon Ltd | Tipton | 2022 |
| Arabian Centers Limited | London | 2024 |
| Araguaney Holdings Limited | London | 2018 |
| Aralbest Limited | Cambridge | 1982 |
| Aram Clothing Ltd | London | 2025 |
| Aramis Computing Services Limited | Brighton | 1984 |
| Aramis GR Limited | London | 2017 |
| Aras Marine Ltd | London | 2025 |
| Arasan Limited | London | 2019 |
| Arav-Viral Limited | Leicester | 2019 |
| Aravind Consultants Limited | Broadstairs | 2013 |
| Araya SIE BBI Nominees Limited | London | 2025 |
| Araya SIE Ventures Nominees Limited | London | 2025 |
| Arazzo Holdings Ltd | London | 2022 |
| ARB Equip Limited | Bridgnorth | 2010 |
| ARB Finance Limited | Northampton | 2023 |
| ARB Motors Limited | Warwick | 2013 |
| ARB Steel Construction Ltd | Scarborough | 2018 |
| Arbar Ltd | Mansfield | 2025 |
| Arbazp Limited | Blackburn | 2022 |
| Arbella House Limited | Rye | 2015 |
| Arbil Properties Ltd | Caerphilly | 2024 |
| Arbiter Bibendi Limited | Shipley | 2005 |
| Arbitrage FBA (UK) Limited | Poole | 2021 |
| Arbitrium Wealth Management Ltd | Doncaster | 2019 |
| Arbm Co 2 Limited | Stoke On Trent | 1975 |
| Arbm Co Limited | Stoke On Trent | 1977 |
| Arbor Garden Products Ltd | Hagley | 2023 |
| Arbor Steel Ltd | London | 2023 |
| Arbormaster Tree and Forestry Services Ltd | Bedford | 2014 |
| Arbortech Professional Tree Services Ltd | Taunton | 1999 |
| Arbory 1960 Limited | Manchester | 2014 |
| Arbourthorne 60 Limited | Sheffield | 2014 |
| Arbra Solutions Ltd | London | 2023 |
| Arbtruck Limited | Tadley | 2006 |
| Arbury Farm Estates Limited | Ilkeston | 2021 |
| Arbury Refrigeration Engineering Limited | Corby | 2022 |
| Arbutus Capital Limited | London | 2016 |
| ARC & Co Structured Finance Limited | London | 2026 |
| ARC Airstreams Limited | Chippenham | 2013 |
| ARC Associates UK Ltd | Hull | 2007 |
| ARC Commercial Energy Services Limited | Harrogate | 2024 |
| ARC Commercial Energy Solutions Limited | Harrogate | 2024 |
| ARC Consultancy & Development Ltd | London | 2020 |
| ARC Digital Media Limited | Heckmondwike | 2012 |
| ARC Engineering Consultants Ltd | Doncaster | 2015 |
| ARC London Ltd | London | 2020 |
| ARC Nominees Limited | Leeds | 2022 |
| ARC Properties NO.1 Ltd | London | 2013 |
| ARC Properties NO.2 Ltd | Kington | 2013 |
| ARC Training and Apprenticeships Limited | Manchester | 2014 |
| Arca Construction Limited | Slough | 2019 |
| Arca Wealth Ltd | London | 2023 |
| Arcabo Limited | London | 2023 |
| Arcadia Cigars Edinburgh Limited | Edinburgh | 2024 |
| Arcadia Cigars Hove Limited | Eastbourne | 2024 |
| Arcadia Cigars Kensington Limited | Hove | 2023 |
| Arcadia Cigars the Lanes Limited | Cardiff | 2022 |
| Arcadia Home Heating Limited | Fakenham | 2020 |
| Arcadia Hotel Limited | Liverpool | 2022 |
| Arcadia Kensington Limited | Redruth | 2023 |
| Arcadia Petroleum Limited | London | 2019 |
| Arcadia Sport Resort Limited | London | 2022 |
| Arcadia Trading Limited | St Albans | 2006 |
| Arcadian Garden Features Limited | Northampton | 1999 |
| Arcane Ventures Ltd | England | 2023 |
| Arcare Homes Limited | Wolverhampton | 2012 |
| Arcare Orton Meadows Limited | Wolverhampton | 2012 |
| Arcens Ltd | London | 2013 |
| Arcera Limited | London | 2026 |
| Arch (UK) Ltd | London | 2014 |
| Arch Building Supplies Limited | Stockton-On-Tees | 1983 |
| Arch Common Land Limited | Cambridge | 2011 |
| Arch Corporation Limited | Godalming | 2013 |
| Arch Manufacturing Company Limited | Cambridgeshire | 1981 |
| Arch Michael Limited | Hove | 2015 |
| Arch Perspective Ltd | London | 2025 |
| Arch Pro Ltd | Gloucester | 2023 |
| Arch Project Management Limited | Manchester | 2016 |
| Arch Technologies Ltd | London | 2023 |
| Archaeological Investigations Limited | Hereford | 2019 |
| Archangel Beats Limited | Altrincham | 2014 |
| Archangel Group Limited | Croydon | 2024 |
| Archangel Holdings Limited | Croydon | 2021 |
| Archangel Informal Investment Limited | Edinburgh | 2014 |
| Archangel Licensing Limited | Exeter | 2018 |
| Archangel Monitoring Ltd | Ossett | 2025 |
| Archangels BBI (KCP Nominees) Limited | London | 2023 |
| Archbold Logistics (Manchester) Limited | Heywood | 2020 |
| Archdere Limited | Bridgend | 2025 |
| Archel Estates Limited | London | 2022 |
| Archerlane | London | 1989 |
| Archers Green 1967 Limited | Mold | 2015 |
| Archery FH Ltd | London | 2016 |
| Archetype M Investments Ltd | Liverpool | 2024 |
| Archibald Campbell Hope & King Limited | Edinburgh | 1965 |
| Archibald Hotel Collection Ltd | Hereford | 2025 |
| Archibald Ltd | London | 2023 |
| Archie Designs Limited | Hailsham | 2014 |