| Atlantic Flight Maintenance Limited | Banbury | 2011 |
| Atlantic House Management Ltd | Sutton Coldfield | 2016 |
| Atlantic House Pension Trustee Limited | Hemel Hempstead | 1977 |
| Atlantic HR Limited | Abbots Langley | 2008 |
| Atlantic International Limited | Stockport | 2008 |
| Atlantic Lightning Black Limited | Blackpool | 2024 |
| Atlantic Merchants Limited | London | 1963 |
| Atlantic Motorcycles Ltd | Bideford | 2025 |
| Atlantic Ocean International Limited | Beckenham | 2019 |
| Atlantic Seafoods International Limited | North Humberside | 1993 |
| Atlantic Speaker Bureau Ltd | Waterlooville | 2013 |
| Atlantic Swiss Bank Limited | London | 2008 |
| Atlantic Trading Estate Management (Barry) Limited | | 1979 |
| Atlantic View Management Company Limited | Portstewart | 1997 |
| Atlanticoside Limited | Glasgow | 2015 |
| Atlantida Enterprises Limited | London | 1977 |
| Atlantide Group Limited | Coventry | 2019 |
| Atlantis Holdings London Limited | Lancashire | 2008 |
| Atlantis Mortgage Solutions Ltd | Birmingham | 2023 |
| Atlantis One Limited | York | 1973 |
| Atlantis Promotions Limited | Dunstable | 1997 |
| Atlantix Developments Ltd | Manchester | 2008 |
| Atlas 110 Limited | Wallington | 2024 |
| Atlas Advanced Internet Solutions Limited | Newark | 2003 |
| Atlas Aerials Limited | Buckinghamshire | 1992 |
| Atlas Aggregates Limited | Coventry | 1935 |
| Atlas Asset Management Ltd | Taunton | 2024 |
| Atlas Audio Ltd. | Bristol | 2022 |
| Atlas Books (Global) Limited | Dorchester | 2023 |
| Atlas Business Software & Technologies Ltd | Crewe | 2009 |
| Atlas Compliance Management Ltd | Epsom | 2024 |
| Atlas Concepts Ltd | London | 2013 |
| Atlas Container Line Limited | Redditch | 1995 |
| Atlas Efes Marine Ltd | London | 2025 |
| Atlas for General Trading Limited | Manchester | 2026 |
| Atlas for International Services Limited | Manchester | 2026 |
| Atlas for International Trading & Services Limited | Manchester | 2026 |
| Atlas for Investment & Trading Ltd | Manchester | 2026 |
| Atlas for Trading Limited | Manchester | 2026 |
| Atlas Global Shipping Line Limited | London | 2016 |
| Atlas International Limited | London | 1995 |
| Atlas International Trading Limited | Manchester | 2026 |
| Atlas Line International Limited | London | 1998 |
| Atlas Packaging Limited | Liverpool | 1983 |
| Atlas PHD Ltd | Westcliff-On-Sea | 2021 |
| Atlas Project Topco Limited | London | 2021 |
| Atlas Restaurant Limited | London | 2003 |
| Atlas Rubber Import&Export Ltd | Beckenham | 2023 |
| Atlas Security Patrol Limited | Birkenhead | 2014 |
| Atlas Sourcing (Asia Pacific) Co., Limited | Cambridge | 2014 |
| Atlas Sportstech Ltd | Tewkesbury | 2020 |
| Atlas Telecom Network (UK) Limited | Leicester | 1998 |
| Atlast a Green Future Limited | Maidenhead | 2021 |
| Atlee Crispin Mitchell Limited | Greenford | 2024 |
| Atluts Limited | Sutton Coldfield | 2022 |
| ATM (Holdings) Limited | Leicester | 1995 |
| ATM Logistics Ltd | Hinckley | 2010 |
| ATM Property Investment Ltd | Glasgow | 2024 |
| ATM Ventures Limited | Glasgow | 2024 |
| Atmali RAF Ltd | Croydon | 2017 |
| Atmaq Limited | Seaton | 2012 |
| Atmc UK Limited | Coalville | 2012 |
| Atmosphere Hot Air Balloons Limited | Winchester | 2019 |
| Atmospheres Services Limited | Bishops Stortford | 2007 |
| Atmospherical Limited | Birmingham | 2016 |
| Atob Executive Ltd | Luton | 2013 |
| Atob Minibuses Ltd | Luton | 2013 |
| Atom Cutting Systems (UK) Ltd | Rushden | 2021 |
| Atom Digital Media Ltd | London | 2023 |
| Atom Digital Solutions Ltd | London | 2023 |
| Atom Global Saas Ltd | Reading | 2024 |
| Atom Mobile Ltd | Newark | 2016 |
| Atomcode Ltd | Welwyn Garden City | 2016 |
| Atomic Corporation Ltd | London | 2024 |
| Atomic Deals Ltd | Mildenhall | 2020 |
| Atomiza Limited | Cheam | 2011 |
| Atomos Global UK Limited | Gerrards Cross | 2022 |
| Atoz Sourcing Ltd | Cambridge | 2014 |
| Atozpropertyconsultants Ltd | London | 2025 |
| ATP Accountants Ltd | Amersham | 2020 |
| ATP Capital Ltd | Southall | 2021 |
| ATP Tennis Ltd | Wimbledon | 1995 |
| ATR Capital Ltd | Maidstone | 2023 |
| ATR Compounding Limited | Westbury | 2008 |
| Atrafloor Limited | Liverpool | 2017 |
| Atrast Compressor (UK) Ltd | Kenilworth | 2019 |
| Atrex Media Ltd | Poole | 2021 |
| Atrion Consulting Solutions Ltd | London | 2012 |
| Atrium Nominees Limited | London | 2015 |
| Atrium Property Services Limited | Oxted | 2021 |
| Atrix Services Limited | Wickford | 2009 |
| Atron MC Limited | London | 2024 |
| Atropa Limited | Rotherham | 2016 |
| ATS Commercial Secretary Limited | London | 2015 |
| ATS Compliance Limited | Kingston Upon Thames | 2015 |
| ATS England Ltd | Pinner | 2018 |
| ATT Associates Limited | Brighton | 2013 |
| Attachview Properties Limited | Guildford | 1982 |
| Attam Limited | Nottingham | 2008 |
| Attenborough & Porter Limited | Glasgow | 2022 |