| Blades Motorcycles Ltd | Winchester | 2024 |
| Blades of Glory Ltd | Worthing | 2024 |
| Bladescombe Investments Limited | London | 1976 |
| Blagden Limited | Westerham | 2009 |
| Blagdon Barton Flats Management Limited | Newton Abbot | 1992 |
| Blaguegate Limited | Skelmersdale | 2015 |
| Blain Pritchard Services Limited | Kent | 2002 |
| Blair Athol Limited | Manchester | 2009 |
| Blair West Topco Limited | Newcastle Upon Tyne | 2026 |
| Blaize-Smith Limited | Harrogate | 2026 |
| Blake Aerials Limited | South Yorkshire | 2002 |
| Blake and White Ltd | Stockbridge | 2020 |
| Blake Holdings Limited | Gateshead | 1993 |
| Blake Performance Fabrics Limited | Rochdale | 1951 |
| Blake Tower City of London Ltd | Barbican | 2022 |
| Blake Veterinary Group Limited | Bristol | 2005 |
| Blakedew 194 Limited | Gillingham | 1999 |
| Blakedown Funeral Services Ltd | Dudley | 2015 |
| Blakedown Landscapes Limited | Woking | 1991 |
| Blakedown Sports Limited | Woking | 1981 |
| Blakeland 1954 Limited | Cambridge | 2013 |
| Blakeney Knitwear Company Limited(The) | Norwich | 1958 |
| Blakes Beginnings Limited | | 1998 |
| Blakes Lavac Taylors Limited | Southampton | 1998 |
| Blakewood Emran Quantity Surveyors Limited | Derby | 2017 |
| Blakkk Limited | Chichester | 2016 |
| Blam Services Limited | Hitchin | 2020 |
| Blanc TOO Limited | Hereford | 1997 |
| Blancflor Limited | London | 2014 |
| Blanchworth Care Homes Limited | Berkeley | 2005 |
| Blanco Y Negro Limited | Sheffield | 1983 |
| Blandford Beer Company Limited | Dorset | 1962 |
| Blandford Neches Ltd | Salford | 2025 |
| Blandy & Blandy Trust Corporation Ltd | | 1994 |
| Blandy Services Limited | | 1994 |
| Blane's Court Management Limited | Hillsborough | 2024 |
| Blanel Limited | London | 2025 |
| Blaney Road Poultry Limited | Newry | 2025 |
| Blanza Group Ltd | London | 2021 |
| Blast and Pressure Cleaning Limited | Manchester | 2025 |
| Blast Clean Systems UK Limited | Melksham | 2014 |
| Blast N Baked Ltd | Street | 2016 |
| Blast Spares Direct Ltd | Blackpool | 2018 |
| Blaster Ltd | Southampton | 2023 |
| Blaster Services Ltd | Kington | 2024 |
| Blastone Holdings (UK) Ltd | London | 2014 |
| Blastsax Limited | Huddersfield | 2015 |
| Blatchfords International Movements Limited | Exeter | 1992 |
| Blatchington Eleven Limited | Birmingham | 1971 |
| Blavod Properties Limited | London | 1999 |
| Blaxill Bros(Builders)Limited | London | 1935 |
| Blaxmill (TEN) Limited | London | 2003 |
| Blayde Security Solutions Ltd | Fareham | 2016 |
| Blayney Financial Limited | Kingston Upon Thames | 2017 |
| Blaze Bourne Ltd | London | 2025 |
| Blaze Digital Limited | Bush Hill Park | 2006 |
| Blaze Tech Studios Limited | Belfast | 2024 |
| Blazebeat Productions Ltd | London | 2025 |
| Blazebeat Sports Ltd | London | 2026 |
| Blazeboard Limited | Reading | 2019 |
| Blazeforge Capital Ltd | Manchester | 2025 |
| Blazenest Capital Ltd | Manchester | 2025 |
| Blazenova Trading Partners Ltd | Manchester | 2025 |
| Blazer Systems Limited | Kent | 2005 |
| Blazespark Trading Solutions Ltd | Manchester | 2025 |
| Blazing K 9'S Ltd | Stoke-On-Trent | 2023 |
| Blazing Marketing Limited | Stoke-On-Trent | 2012 |
| BLC Marine Ltd | London | 2021 |
| Blding Ltd | Bristol | 2019 |
| Bleachgreen Apartments Limited | Coleraine | 2008 |
| Blears Limited | London | 2014 |
| Bleat and Cream Ltd | London | 2025 |
| Blen Ltd | Leeds | 2013 |
| Blencathra Nominees Limited | Bristol | 2009 |
| Blencowe Lime Co.,Limited(The) | Carlisle | 1936 |
| Blend App Limited | Hamilton | 2020 |
| Blendcheck Limited | Burntwood | 2011 |
| Blendcross Holdings Limited | London | 2022 |
| Blendcross Investments (Holdings) Limited | London | 2022 |
| Blended Beginnings Ltd | Bristol | 2023 |
| Blended by Design Ltd | Liverpool | 2023 |
| Blended First AID Ltd | Hassocks | 2023 |
| Blended IO Ltd | London | 2025 |
| Blenham Investments Limited | London | 2024 |
| Blenheim Court Hove RTM Company Limited | Hove | 2026 |
| Blenheim Gate (Maidstone) Management Company Limited | Bourne End | 1998 |
| Blenheim Gate (Woodstock) NO. 2 Management Limited | Henley-On-Thames | 2008 |
| Blenheim Management Consultancy Ltd | Meopham | 2017 |
| Blenheim Veterinary Centre Limited | Bristol | 2008 |
| Bleruskin UK Personal Care Products Co., Ltd | Beckenham | 2026 |
| Blesbio Ltd | London | 2024 |
| Bless Apparel Co., Ltd | Beckenham | 2015 |
| Bless Sweden Limited | London | 2020 |
| Bless Villa Limited | Glasgow | 2024 |
| Blessarm Ltd | Northampton | 2022 |
| Blessed Records Ltd | London | 2005 |
| Blessedduo Limited | Sheffield | 2018 |
| Blessing Marine Ltd | Blackpool | 2024 |
| Blessings in Disguise Limited | Leigh | 2013 |
| Blessure Ltd | London | 2024 |