| Atis Holdings Limited | Bath | 2025 |
| Ativa Holdings Limited | London | 2016 |
| ATJ Prop Limited | Stonehaven | 2016 |
| ATK Business Solutions Limited | Leeds | 2025 |
| ATK Collective Ltd | Cumnock | 2026 |
| ATK Corporate Solutions Limited | London | 2015 |
| ATK Investment Holdings Limited | Manchester | 2025 |
| ATK Property Group Limited | Perthshire | 2021 |
| ATK Property Ltd | Bury St Edmonds | 2021 |
| Atkey Holdings Limited | Sheffield | 2017 |
| Atkin Holdings Limited | London | 2022 |
| Atkinberry Holdings Ltd | Hindhead | 2026 |
| Atkins & Co. Connections Ltd | Daventry | 2025 |
| Atkins Bland Limited | Ferndown | 1995 |
| Atkins Capital Limited | Dunmow | 2013 |
| Atkins Corporate Holdings Limited | London | 2022 |
| Atkins Family Holdings Limited | Sidcup | 2025 |
| Atkins Financial Solutions Limited | Kenley | 2010 |
| Atkins Home Solutions Ltd | Newcastle | 2025 |
| Atkins Investment Group Limited | Swansea | 2023 |
| Atkins Properties Limited | Liphook | 1961 |
| Atkins Special Risks Limited | Caterham | 1995 |
| Atkins Wealth Consultancy Ltd | Halesowen | 1999 |
| Atkinson & Lockyer Limited | Sutton Coldfield | 2023 |
| Atkinson & Sellar Group Ltd | Linwood | 2022 |
| Atkinson Broking Solutions Limited | Newport | 2014 |
| Atkinson Business Services Limited | Wimborne | 2014 |
| Atkinson Equipment Group Limited | Westbury | 2021 |
| Atkinson F Holdings Ltd | Chesterfield | 2025 |
| Atkinson Family Investment Company Unlimited | Huddersfield | 2019 |
| Atkinson Financial Services Limited | Barrow-In-Furness | 2019 |
| Atkinson Group (Yorkshire) Limited | Horsforth | 2016 |
| Atkinson Group Investments Ltd | South Kirby | 2026 |
| Atkinson Holdings Limited | Horsforth | 1998 |
| Atkinson Property Solutions Limited | Greenock | 2020 |
| Atko Holdings Limited | Bedford | 2026 |
| Atko Investments Ltd | Bedford | 2026 |
| ATL Agriserve Limited | Newmarket | 2012 |
| ATL Marine & Energy Limited | London | 2012 |
| ATL Property Group Ltd | Glasgow | 2026 |
| ATL Property Ltd | Leeds | 2022 |
| ATL Royalties Ltd | Walsall | 2024 |
| ATL Technology UK Holdings Limited | London | 2023 |
| ATL Trustees Ltd | Oldbury | 2017 |
| Atlafamily Limited | Manchester | 2025 |
| Atlam Financial Services Limited | London | 2002 |
| Atlanco Management Ltd | London | 2022 |
| Atlant Maritime Ltd | London | 2025 |
| Atlanta 1 Insurance Services Limited | Stoke-On-Trent | 1998 |
| Atlanta Enterprises Limited | Cardiff | 2023 |
| Atlanta Insurance Intermediaries Limited | Salford | 1963 |
| Atlanta Investment Holdings 2 Limited | Burslem | 2016 |
| Atlanta Investment Holdings 3 Limited | Salford | 2016 |
| Atlanta Investment Holdings a Limited | Burslem | 2017 |
| Atlanta Investment Holdings B Limited | Burslem | 2018 |
| Atlanta Investment Holdings D Limited | Burslem | 2020 |
| Atlanta Investment Holdings D3 Limited | Burslem | 2021 |
| Atlanta Investment Holdings Limited | Burslem | 2016 |
| Atlanta Investment Holdings Midco B Limited | Burslem | 2018 |
| Atlanta Investments Holdings D1 Limited | Burslem | 2020 |
| Atlanta MGA Holdings Limited | London | 2022 |
| Atlanta Proptrading North Ltd | London | 2026 |
| Atlantechs Holdings Ltd | Towcester | 2015 |
| Atlantian Crown BK Limited | London | 2025 |
| Atlantic Alliance Limited | London | 2003 |
| Atlantic and Dominion Limited | London | 2015 |
| Atlantic Arbitrage Ltd | Sevenoaks | 2025 |
| Atlantic Assets Trust Limited | Edinburgh | 2008 |
| Atlantic Automate (UK) Limited | London | 2017 |
| Atlantic Bidco Limited | Houghton Le Spring | 2018 |
| Atlantic Blue Holdings Limited | Sheffield | 2019 |
| Atlantic Breeze Financial Limited | London | 2013 |
| Atlantic Capital Advisory Limited | London | 2022 |
| Atlantic Capital Ltd | Gerrards Cross | 2023 |
| Atlantic Capital Markets Ltd | Truro | 2016 |
| Atlantic Carosserie Ltd | London | 2014 |
| Atlantic Coast Associates (Cornwall) Limited | Newquay | 2014 |
| Atlantic Coast Associates (Redruth) Limited | Redruth | 2019 |
| Atlantic Communications Limited | Tithebarn Street | 1982 |
| Atlantic Development Projects Limited | Newcastle | 2019 |
| Atlantic Equity Holding Limited | Uckfield | 2019 |
| Atlantic Family Holdings Ltd | Clacton-On-Sea | 2023 |
| Atlantic Financials Ltd | London | 2018 |
| Atlantic Funding Limited | London | 2026 |
| Atlantic Gateway Initiative Limited | Northampton | 2025 |
| Atlantic GP 1 Limited | London | 2018 |
| Atlantic GP 2 Limited | London | 2018 |
| Atlantic Granville Ltd | London | 2017 |
| Atlantic Group Services Limited | Liverpool | 2022 |
| Atlantic Horizon Ltd | Lincoln | 2025 |
| Atlantic House Group Limited | Birmingham | 2015 |
| Atlantic House Holdings Limited | Birmingham | 2021 |
| Atlantic House Investments Limited | Birmingham | 2019 |
| Atlantic Intermediaries UK Limited | London | 2025 |
| Atlantic Investments Holdings Limited | Liverpool | 2023 |
| Atlantic Management Ltd | Cardiff | 2020 |
| Atlantic Metals Limited | London | 2024 |
| Atlantic Midco Limited | Houghton Le Spring | 2018 |
| Atlantic Ocean Design Ltd | Egham | 2018 |
| Atlantic PLG Limited | West Malling | 2018 |