| BTR Group Holdings Limited | Wolverhampton | 2025 |
| BTR Group Limited | Wembley | 2025 |
| BTR Industries Limited | Telford | 1950 |
| BTR Reit Ltd | Harrogate | 2019 |
| Btrotman Ltd | Paignton | 2025 |
| BTS &Co Ltd | Nottingham | 2025 |
| BTS Facades and Fabrications Holdings Limited | Newton Aycliffe | 2025 |
| BTS Group Services Ltd | Hatch End | 2022 |
| BTS Holdco Ltd | London | 2024 |
| BTS Specialised Equipment Limited | Stockport | 1996 |
| Btsco Limited | Stockton-On-Tees | 2017 |
| Btsg Property Services Ltd | Hitchin | 2025 |
| BTT Holdings Limited | Goole | 2018 |
| BTU Group Limited | Guildford | 2025 |
| BTU Holdings Limited | Guildford | 2022 |
| BTW Financial Services Limited | Leicester | 2018 |
| BTW Group Holdings Ltd | Leigh On Sea | 2024 |
| BTW Group Investments Ltd | Dudley | 2026 |
| BTW Group Ltd | Fordingbridge | 2026 |
| BTW Holdings and Investments Ltd | Dudley | 2019 |
| BTW Holdings Ltd | Dudley | 2025 |
| BTW Mortgages Ltd | Danderhall | 2026 |
| Btxx Ltd | Cambridge | 2025 |
| BU - Business Unlimited Worldwide Ltd. | London | 2024 |
| BU Bregal Unternehmerkapital UK Ltd | London | 2024 |
| BUA (Holdings) Ltd | Birmingham | 2020 |
| Buabeng & Silva Ltd | Slough | 2026 |
| Buachaille Holdings Limited | Kirkby Stephen | 2016 |
| Buacom Ltd | Sevenoaks | 2002 |
| Buadu Corp Ltd | London | 2016 |
| Buaic ARD Ltd | Glenrothes | 2021 |
| Buan Holdings Ltd | Edinburgh | 2026 |
| Bubba Holdings Ltd | Nottingham | 2025 |
| Bubba Investments Ltd | Waltham Cross | 2022 |
| Bubble Brands Limited | Doncaster | 2014 |
| Bubble Finance Hub Limited | Hinckley | 2019 |
| Bubble Finance Limited | Edgbaston | 2018 |
| Bubble Financial Limited | Cannock | 2025 |
| Bubble Media Ltd | Burton-On-Trent | 2019 |
| Bubblebum Holdings Limited | Londonderry | 2012 |
| Bubblegum Frangipani Holdings | Bromsgrove | 2019 |
| Bubbles Asset Finance Limited | Cardiff | 2021 |
| Bubbles Pank Limited | Norwich | 2023 |
| Bubblewrap Holding Limited | London | 2019 |
| Bubby Ltd | London | 2022 |
| Buben Investments Group Holdings Ltd | Huntingdon | 2019 |
| Bubhurst Ltd | Cranbrook | 2021 |
| Bubney Farms Holding Ltd | Whitchurch | 2023 |
| Bubo Holdings Ltd | Liverpool | 2025 |
| Bubu Investment Ltd | London | 2023 |
| Buccaneer Bidco Limited | Reading | 2018 |
| Buccaneer Holdco Limited | Reading | 2018 |
| Buccaneer Intermediate Holdco Limited | Reading | 2018 |
| Buccaneer Midco Limited | Reading | 2018 |
| Buccaneer Subco Limited | Reading | 2018 |
| Bucchinc Ltd | Waterlooville | 2020 |
| Buccleuch Estates, Ltd. (the) | Selkirk | 1923 |
| Bucco Nero Holdings Ltd | Glasgow | 2026 |
| Bucephalas Ltd | Wirral | 2022 |
| Buchan 1 Limited | Aberdeen | 2019 |
| Buchan 2 Limited | Aberdeen | 2019 |
| Buchan Investments Limited | Chippenham | 1998 |
| Buchanan & Associates Financial Planning Limited | Edinburgh | 2009 |
| Buchanan & Company Financial Services Limited | Sale | 2020 |
| Buchanan Commercial Ltd | Paisley | 2025 |
| Buchanan Consulting SW Ltd | Exeter | 2017 |
| Buchanan Cowie Ltd | Gosport | 2020 |
| Buchanan Family Investment Company Limited | Huntingdon | 2025 |
| Buchanan Financial Group Ltd | Glasgow | 2018 |
| Buchanan Financial Planning Ltd | Glasgow | 2023 |
| Buchanan Group Holdings Limited | Waterlooville | 2021 |
| Buchanan Holco Limited | Manchester | 2026 |
| Buchanan Investments Limited | Lochgelly | 2024 |
| Buchanan Johnston Flynn Limited | Belfast | 2004 |
| Buchanan Lloyd Group Limited | Manchester | 2023 |
| Buchanan MS Holdings Ltd | Glasgow | 2019 |
| Buchanan Properties (Holdings) Ltd | Hereford | 2026 |
| Buchanhaven Holdings 2020 Limited | Aberdeen | 2020 |
| Buchanhaven Holdings 2024 Ltd | Aberdeen | 2024 |
| Bucharest Bidco Limited | York | 2018 |
| Bucharest Holdco Limited | York | 2018 |
| Bucharest Midco Limited | York | 2018 |
| Bucharest Topco Limited | York | 2018 |
| Bucher & Behrens Holdings Ltd | London | 2023 |
| Bucherer Holding Limited | London | 2017 |
| Buchmann Ventures Ltd | Tunbridge Wells | 2023 |
| Buchner Holdings Limited | Lincoln | 2019 |
| Buchu Business Services Ltd | Crawley | 2019 |
| Buck Asset Group Ltd | Stowmarket | 2025 |
| Buck Estates Holdings Limited | Ipswich | 2021 |
| Buck Estates Linden Road Ltd | Ipswich | 2023 |
| Buck Holdings Ltd | Fareham | 2023 |
| Buck Media Group Ltd | London | 2025 |
| Buck Wealth Management Limited | Newark | 2017 |
| Bucket MAN Limited | Harrogate | 2025 |
| Buckets Investment Company | Belfast | 2026 |
| Buckfield Holdings Ltd | Fareham | 2018 |
| Buckham Heath Ltd | Chichester | 2021 |
| Buckhead Capital UK Holdings Ltd | Cockermouth | 2020 |
| Buckhill (Holding) Limited | London | 2020 |