| Arigma Contracting (Private) Limited | London | 2026 |
| Arimo Glow UK Ltd | London | 2025 |
| Arinze Antigha Okosieme | Bury St. Edmunds | 2024 |
| Arion Estates Limited | Haverhill | 1993 |
| Arion Shop Ltd | Sleaford | 2024 |
| Aris & Bella Ltd | Pimlico | 2017 |
| Aris Financial Limited | Witham | 2016 |
| Arisaig Wealth Management Ltd | Exeter | 2024 |
| Arisaviewtour Ltd | Sidcup | 2025 |
| Arise Recruitment Agency Limited | Wallington | 2021 |
| Ariseandsoar Limited | Coventry | 2021 |
| Arista Corporation Limited | Suffolk | 1999 |
| Aristan Realty Limited | Manchester | 2024 |
| Aristo Associates Limited | London | 2024 |
| Aristocat Properties Limited | Princes Risborough | 2009 |
| Ariston Accommodation Limited | | 1996 |
| Ariston Appliances (Italy) Co., Ltd. | Kenilworth | 2017 |
| Ariston Property Management Ltd | London | 2014 |
| Arisure Consultancy Limited | Loughborough | 2018 |
| Arisure Limited | Loughborough | 2018 |
| Aritar Limited | Lisburn | 2021 |
| Aritari Limited | London | 2014 |
| Arjay Plumbing Limited | Waterlooville | 2016 |
| Arjen Kuiper Coaching Limited | London | 2023 |
| Arjun Holding Ltd | Ealing | 2019 |
| ARK and General Limited | Huntingdon | 1989 |
| ARK Asset Management Ltd | Coventry | 2016 |
| ARK Associates Ltd | Birmingham | 2013 |
| ARK Biomass Limited | Boston | 2017 |
| ARK Commercial Motor Limited | Coventry | 2016 |
| ARK Community Payroll Limited | Birkenhead | 2014 |
| ARK Concoction Ltd | London | 2025 |
| ARK Coworking Ltd | London | 2016 |
| ARK Delicious Holdings Ltd | Watford | 2025 |
| ARK Fabricators Limited | Boston | 2011 |
| ARK Furniture Limited | Manchester | 2020 |
| ARK House Vets Limited | Bristol | 2010 |
| ARK Real Estate Group Ltd | Birmingham | 2024 |
| ARK Royale Property Ltd | Hartlepool | 2024 |
| ARK Veterinary Centre (Colchester) Limited | Bristol | 2014 |
| Arkadiusz Maciej Kulesza Ltd | Nottingham | 2024 |
| Arkana Limited | London | 2017 |
| Arkco (UK) Limited | Wood Green | 2004 |
| Arkcroft Limited | Wroxham | 1993 |
| Arke SPV 1 Limited | Halifax | 2015 |
| Arkell Land Ltd | Swindon | 1914 |
| Arkfield Limited | Salford | 2000 |
| Arkham Industries Ltd | Loughborough | 2018 |
| Arkmile Limited | London | 2006 |
| Arknowledge Limited | Nottingham | 2015 |
| Arkonik.Com Limited | Plymouth | 2014 |
| Arkwood Projects Ltd | Liverpool | 2010 |
| Arkwright and Co Limited | Cardiff | 1991 |
| Arkwright Finance Limited | London | 1987 |
| Arkwright Homes Limited | London | 1987 |
| Arkwright Planning Limited | London | 1987 |
| ARL (NE) Ltd | Darlington | 2014 |
| ARL Farming Ltd | Kelso | 2012 |
| Arla Foods Life Assurance Trustees Limited | Leeds | 2009 |
| Arla Foods Pension Plan Trustees Limited | Leeds | 1998 |
| Arlec UK Holdings Limited | Rugby | 1996 |
| Arlee Developments Limited | Belfast | 1996 |
| Arlene Davina Coley Limited | London | 2023 |
| Arlene Sophia Michelle Swaby Ltd | Northampton | 2025 |
| Arlesey Trading Limited | Craigavon | 1974 |
| Arlingclose Services Limited | Stratford-Upon-Avon | 2013 |
| Arlington Davies Ltd | Preston | 2006 |
| Arlington House Management Company Limited | Shepton Mallet | 1991 |
| Arlington Place Limited | London | 2011 |
| Arlington Property Company Limited | Liverpool | 1982 |
| Arlington Road NO 31 Limited | London | 2005 |
| Arlo Creative Limited | London | 2023 |
| Arlowe Drive Management Company Limited | Oxford | 2010 |
| ARM Interior Design Company Ltd | West Midlands, England | 2023 |
| ARM Investment Management Ltd | Edinburgh | 2012 |
| Arma Yachting Ltd | Blackpool | 2025 |
| Armaan Foods (UK) Limited | Leicester | 2013 |
| Armac Holdings Limited | York | 2020 |
| Armack Limited | Bury | 2020 |
| Armada Associates Limited | Bury | 2020 |
| Armada Real Estate Ltd | Bridgend | 2015 |
| Armadillo Container Storage Ltd | London | 2025 |
| Armadillo Garage Doors Ltd | Staines Upon Thames | 2024 |
| Armadillo Roofing Ltd | Staines Upon Thames | 2024 |
| Armadillo Services Ltd | Bedford | 2015 |
| Armage Ltd | Chatham | 2026 |
| Armagh Assets (NO 2) Limited | Manchester | 2016 |
| Armagh Assets (NO 3) Limited | Manchester | 2016 |
| Armagh Builders Providers Limited | Co Armagh | 1979 |
| Armagh Horticultural Limited | Co.Tyrone | 1975 |
| Armagh Self Storage Ltd | Portadown | 2021 |
| Armandas Malisauskas Limited | Kettering | 2022 |
| Armani Hotels Limited | Borehamwood | 2018 |
| Armani Properties Limited | Potters Bar | 2003 |
| Armasan Co., Ltd | London | 2017 |
| Armashield Limited | Waterlooville | 2016 |
| Armco Chemical Global Ltd | Beckenham | 2020 |
| Armcon Trading Limited | Poynton | 2016 |
| Armed & Gorgeous Limited | Stroud | 2015 |
| Armed Forces Covenant Fund Trustee Limited | Leeds | 2018 |