| Atlas Operations Ltd | London | 2022 |
| Atlas Partners (Hastings) 1 Ltd | Poole | 2016 |
| Atlas Partners (Sydenham) Ltd | Orpington | 2015 |
| Atlas Partners Group Limited | Canterbury | 2016 |
| Atlas Peak International Ltd | London | 2021 |
| Atlas Personal Training Limited | Manchester | 2026 |
| Atlas Recyclers 2 Limited | Sydenham | 1988 |
| Atlas Recyclers Limited | Belfast | 1975 |
| Atlas Refurb + Repair Limited | Bilston | 2013 |
| Atlas Safety Management Limited | Wellington | 2015 |
| Atlas Services Centre Limited | London | 2023 |
| Atlas Shipping and Logistics Company Ltd | Edinburgh | 2018 |
| Atlas Shop Ltd | London | 2025 |
| Atlas Solutions Limited | London | 2024 |
| Atlas SP UK Services Limited | London | 2023 |
| Atlas Suppliers Limited | Barnet | 2024 |
| Atlas Surfaces Ltd | London | 2025 |
| Atlas Trading & Services Ltd | London | 2015 |
| Atlas Transporte Ltd | Luton | 2018 |
| Atlas Ventures Group Limited | Portsmouth | 2017 |
| Atlas' Grooming PAD Ltd | Peterlee | 2026 |
| Atlas-X Ltd | London | 2024 |
| ATLAS27 Ltd | Bognor Regis | 2026 |
| Atlasor Ltd | Harrow | 2024 |
| Atleast Limited | London | 2018 |
| Atlin Seating Limited | Cambridge | 2015 |
| ATM Cleaning Limited | Stevenage | 2018 |
| ATM Commissions Limited | Falkirk | 2019 |
| ATM Corporate Events Limited | Bradford | 2001 |
| ATM Events Limited | Salisbury | 2018 |
| ATM Property Services Limited | Liverpool | 2015 |
| ATM X Ltd | Walsall | 2024 |
| Atma Happy Limited | Milton Keynes | 2024 |
| Atma Skin Ltd | Nottingham | 2026 |
| Atman House Ltd | Folkestone | 2023 |
| Atman Retail Ltd | Sevenoaks | 2013 |
| Atmar & Co. Ltd | Ilford | 2025 |
| Atmcc Trade Limited | London | 2018 |
| Atmi Bakery Ltd | London | 2025 |
| Atmos Barbering Ltd | Motherwell | 2025 |
| Atmosan Limited | Farnborough | 2020 |
| Atmosphee Ltd | Bury St. Edmunds | 2023 |
| Atmosphere Environmental Limited | Hebden Bridge | 2009 |
| Atmoss Limited | Shipley | 2009 |
| Atmp Manufacturing Community Limited | Durham City | 2015 |
| ATN Global Limited | Manchester | 2019 |
| ATN Group Limited | Leigh | 2019 |
| Atnd Services Limited | Wigan | 2020 |
| Atnl Limited | London | 2025 |
| ATO Productions Limited | London | 2018 |
| ATO Studio Ltd | Rickmansworth | 2021 |
| Atob Services Ltd | London | 2019 |
| Atobaah Co Ltd | Liverpool | 2019 |
| Atog Group Ltd | London | 2023 |
| Atogdina & Co Ltd | London | 2015 |
| Atoll Protection Limited | Chelmsford | 2019 |
| Atolls London Limited | London | 2017 |
| Atom & IVY Studio Ltd | Barnsley | 2026 |
| Atom Aesthetics Limited | Ilford | 2023 |
| Atom Events Limited | London | 2002 |
| Atom Facilities Management Ltd | Leicester | 2024 |
| Atom Fit OUT Construction & Design Ltd | Leicester | 2024 |
| Atom Food & Drink Ltd | Leicester | 2024 |
| Atom Music Events Ltd | Flixton | 2020 |
| Atom Parkhaus Ltd | Farnborough | 2024 |
| Atomic .Inc Ltd | Plymouth | 2017 |
| Atomic Alloys Limited | Basildon | 2019 |
| Atomic Blonde Limited | London | 2024 |
| Atomic Fitness Ltd | Thatcham | 2014 |
| Atomic Hair Limited | Didcot | 2010 |
| Atomic Locksmiths Ltd | Dundee | 2025 |
| Atomic Plant and Surfacing Ltd | Ashton-Under-Lyne | 2015 |
| Atomic Spa Ltd | Hull | 2019 |
| Atomic Squib Limited | Faversham | 1998 |
| Atomic Supersonic Limited | London | 2000 |
| Atomist | Isle Of Lewis | 2019 |
| Atomium Electronics Limited | Newcastle | 1977 |
| Atomlink Limited | Amersham | 2017 |
| Atoms Events UK Ltd | Southend On Sea | 2023 |
| Atoms Scooters Ltd | Sandling | 2021 |
| Atomy Global Care Centre Ltd | Solihull | 2023 |
| Atomyc Ltd | Aylesbury | 2023 |
| Atoro 18 Limited | Wilmslow | 2023 |
| Atosuk Services Ltd | London | 2012 |
| Atoun RUG Cleaning Ltd | Liverpool | 2024 |
| Atousa Aesthetics Ltd | London | 2024 |
| Atoz Business Ltd | Hayes | 2025 |
| Atoz Impex Limited | Milton Keynes | 2022 |
| ATP Heating Services Limited | Chelmsford | 2007 |
| ATP Van Hire Limited | Brierley Hill | 2015 |
| Atpc Consulting Ltd | Edinburgh | 2019 |
| Atps (London - SW) Ltd | Oxon | 2011 |
| Atputha Vinayagar | Wembley | 2017 |
| ATR Auto Services Limited | Eastbourne | 2017 |
| ATR Properties Limited | Sutton Coldfield | 2007 |
| ATR Repairs Domestic & Commercial Ltd | Edinburgh | 2021 |
| Atra Europe Ltd | Hailsham | 2023 |
| Atree (NW) Ltd | Blackburn | 2019 |
| Atrium Professional Services Ltd | London | 2013 |
| Atro Ltd | London | 2022 |