| Buff RE Ltd | Broadstairs | 2025 |
| Buffalo Battery Metals (UK) Ltd | London | 2022 |
| Buffalo Bidco UK Limited | London | 2022 |
| Buffalo Soldiers Limited | London | 2005 |
| Buffalo Topco UK Limited | London | 2022 |
| Buffavento Limited | Harrow | 2014 |
| Buffett Finance Limited | Mayfair | 2024 |
| Buffettique Ltd | Bristol | 2023 |
| Bufield Consultants Limited | Cannock | 2014 |
| BUG and Bean Holdings Ltd | London | 2025 |
| Buggaboo Ltd | Winchester | 2021 |
| Buggy Dough Limited | Oldham | 2017 |
| Buggy-Inv Ltd | Chislehurst | 2021 |
| Buglass Holdings Limited | Blyth | 2019 |
| Bugler Properties Limited | Yeovil | 2019 |
| Bugs Investment Limited | Bath | 2022 |
| Bugshan British Company Limited | London | 2022 |
| Bugsy Investments Ltd | London | 2025 |
| Buha Ltd | Manchester | 2025 |
| Buhmi Ltd | East Grinstead | 2019 |
| Buick Media Limited | Belfast | 2026 |
| Buick Morgan FS Holdings | London | 2022 |
| Buidhe Holdings Ltd | Petersfield | 2024 |
| Build & Developments (Holdings) Limited | London | 2020 |
| Build 4 Growth Holdings Limited | Sheffield | 2022 |
| Build a Solution Holdings Ltd | Cannock | 2024 |
| Build Capital Limited | London | 2011 |
| Build Finance Limited | Potters Bar | 2017 |
| Build Financial Plan Ltd | Macclesfield | 2023 |
| Build Munos Limited | Cambridge | 2016 |
| Build OUT Cover Claims Ltd | Livingston | 2016 |
| Build OUT Cover Ltd | Livingston | 2016 |
| Build Partnership Group Limited | Maidenhead | 2025 |
| Build Pro (EM) Limited | Melton Mowbray | 2014 |
| Build Right Holdings U.K. Ltd | Birmingham | 2023 |
| Build Secure INS Ltd | Durham | 2021 |
| Build Secure Ltd | Durham | 2021 |
| Build Team (Holdings) Ltd | London | 2014 |
| Build Tomorrow's Home Today Ltd | Salisbury | 2019 |
| Build Trust Group Limited | Potters Bar | 2024 |
| Build Warranty Insurance Services Ltd | Gateshead | 2018 |
| Build Wise Capital Ltd | Morden | 2026 |
| Buildbunk Ltd | London | 2020 |
| Builders by Design Holdings Ltd | London | 2023 |
| Builders D J Limited | Weymouth | 2014 |
| Builders Merchant Supplies Ltd | Blackburn | 2020 |
| Buildfuture Holdings Ltd | Waltham Cross | 2026 |
| Buildguard Escrow Client Money Limited | Hook | 2026 |
| Buildguard Escrow Limited | Hook | 2026 |
| Building 400 Limited | London | 2005 |
| Building Again 2024 Limited | Wilmslow | 2024 |
| Building and Civil Engineering Benefits Scheme Trustee Limited | West Sussex | 1975 |
| Building and Land Guarantees Holdco Limited | London | 2023 |
| Building and Land Guarantees Limited | London | 2006 |
| Building Arch Ltd | London | 2024 |
| Building Big Things Ltd | Newbury | 2018 |
| Building Blocks Group Limited | Manchester | 2025 |
| Building Civil Engineering Holdings Ltd | Hamilton | 2025 |
| Building Claims Services Limited | Taunton | 2003 |
| Building Construction Partnership Group Ltd | Wakefield | 2019 |
| Building Construction Partnership Holdings Ltd | Wakefield | 2025 |
| Building Consultancy Group Limited | Birmingham | 2025 |
| Building Finance Limited | Preston | 2016 |
| Building Funding Solutions Limited | London | 2014 |
| Building Future Investments Limited | Hove | 2024 |
| Building Group Finance Limited | Doncaster | 2020 |
| Building Intelligence Limited | London | 2002 |
| Building Interiors Holdings Limited | Leeds | 2016 |
| Building Lifeplans Limited | London | 1999 |
| Building Plastics Direct Holdings Limited | Barnsley | 2018 |
| Building Rapport Housing Ltd | Birmingham | 2022 |
| Building Reinstatement Valuation Services Ltd | Oxted | 2022 |
| Building Rockets Ltd | Truro | 2021 |
| Building Services Compliance Group Ltd | Charlwood | 2024 |
| Building U Solutions Ltd | Mildenhall | 2024 |
| Buildingis (Holdings) Limited | Romsey | 2020 |
| Buildloan Limited | Livingston | 2013 |
| Buildmatch Group Ltd | London | 2025 |
| Buildpave Holdings Ltd | Bolton | 2021 |
| Buildr Capital Ltd | Ruislip, | 2020 |
| Buildstone Limited | London | 2026 |
| Buildstore Insurance Services Limited | Livingston | 2013 |
| Buildstore Mortgage Services Limited | Livingston | 2013 |
| Buildtex Holdings Ltd | Norwich | 2022 |
| Built Consulting Ltd | Portsmouth | 2024 |
| Built Cybernetics PLC | London | 1987 |
| Built Environment Group Limited | Sleaford | 2016 |
| Built Square Group Limited | Rodborough | 2020 |
| Built Venture Capital Limited | Liverpool | 2018 |
| Built-To-Last Investments Limited | London | 2026 |
| Builtform Holdings Limited | Chandlers Ford | 2017 |
| Builth Wells Financial Planning Limited | Builth Wells | 2005 |
| Builth Wells Financial Services Limited | Builth Wells | 2002 |
| Builtvisible Holdings Limited | London | 2019 |
| Buipe Ltd | London | 2019 |
| Buitenzorg Limited | London | 2025 |
| BUK Fashion HOLDINGS2 Limited | London | 2024 |
| BUK Trading Ltd | Sutton St Edmund | 2019 |
| Bukhari Holdings Ltd | Sutton Coldfield | 2020 |
| Bukhari Property Holding Limited | Slough | 2025 |