| Bletchley Recycling Limited | Graveley | 2014 |
| Bletchley Skip Hire Limited | Graveley | 2014 |
| Bleufire Ltd | London | 2025 |
| Blewbury Road Orchard Ltd | Didcot | 2021 |
| Blhd Ltd | Bournemouth | 2024 |
| Blick Dormants Limited | Rotherham | 1963 |
| Blick Engineering Limited | Rotherham | 1949 |
| Blick Group Management Services Limited | Rotherham | 1977 |
| Blick International Limited | Rotherham | 1977 |
| Blick International Systems Limited | Rotherham | 1926 |
| Blick Maintenance Limited | Rotherham | 1951 |
| Blick Music Ltd | London | 2024 |
| Blick National Systems Limited | Rotherham | 1964 |
| Blick Properties Limited | Rotherham | 1943 |
| Blick Software Systems Limited | Rotherham | 1982 |
| Blick Tannoy Limited | Rotherham | 1958 |
| Blick Telefusion (Scotland) Limited | Aberdeen | 1976 |
| Blick Telefusion Communications Limited | Rotherham | 1980 |
| Blick Time Recorders Limited | Rotherham | 1979 |
| Blick Time Systems Limited | Rotherham | 1933 |
| Blighty Manufacturing Limited | Redditch | 2021 |
| Blincow Dispute Solutions Ltd | Gourock | 2020 |
| Blind Children UK (Trading) Limited | Reading | 2001 |
| Blind Inspiration Limited | Norwich | 2001 |
| Blinder Bunker International Limited | Shaftesbury | 2012 |
| Blinds "R" US Limited | Pyle Bridgend | 2002 |
| Blinds in Glass Limited | Nuneaton | 2020 |
| Bling Clean Ltd | Dudley | 2024 |
| Blink Optical Limited | Llandudno | 2014 |
| Blink Reservations Limited | Gloucester | 2006 |
| Blinkbonny Quarry (Borders) Limited | Monifieth | 2000 |
| Blipit Limited | Sevenoaks | 2011 |
| Bliss Clinic Limited | High Wycombe | 2000 |
| Bliss England Limited | Sutton Coldfield | 2013 |
| Bliss Ice Cream Limited | Newport | 2020 |
| Bliss Interior Systems Limited | Wimborne | 1991 |
| Bliss Star Limited | Newton Abbot | 2012 |
| Bliss Yoga Limited | Bath | 2022 |
| Blissbalance Wellness Ltd | Ipswich | 2026 |
| Blissful Horizons Capital Ltd | Manchester | 2025 |
| Blissfulbalance Ltd | London | 2025 |
| Blissfulbalance Wellness Ltd | London | 2026 |
| Blissio Limited | Stockport | 2009 |
| Blisworth Caravans Limited | London | 1962 |
| Blisworth Hill Finance Ltd | Towcester | 2023 |
| Blisworth Hill Services Ltd | Towcester | 2023 |
| Blitz Floor Cleaning Ltd | Bishop Auckland | 2025 |
| Blivale Ltd | London | 2024 |
| Blixt VVS Sweden Limited | London | 2013 |
| Blizzard Limited | Bournemouth | 2001 |
| BLJ Property Investments Ltd | Corby | 2022 |
| BLK Limited | Kettering | 1946 |
| BLL Limited | Kettering | 1966 |
| BLL Supply Chain Co., Ltd | Beckenham | 2014 |
| BLM Author Limited | Stanmore | 2012 |
| Blme Asset Management Limited | London | 2008 |
| Blme Holdco Limited | London | 2013 |
| Blme Limited | London | 2007 |
| Bloblogic Limited | Lydney | 2012 |
| Bloc Creative Ltd | Derby | 2020 |
| Bloc Graphics Limited | Derby | 2018 |
| Bloc Nominee (Bridgerton) Limited | London | 2021 |
| Block 1 Management Company Limited | Dunstable | 2024 |
| Block 9 Hyde Park Mansions Ltd | London | 2023 |
| Block Feng Limited | Cardiff | 2021 |
| Block House Mining Ltd | Folkestone | 2022 |
| Block House XYZ Ltd | Folkestone | 2022 |
| Block IND Devs CC 1 Limited | London | 2022 |
| Block IND Props CC Limited | London | 2022 |
| Block Industrial CC 2 Limited | London | 2022 |
| Block Industrial CC 3 Limited | London | 2022 |
| Block Industrial CC 4 Limited | London | 2024 |
| Block-Fox Ltd | Glasgow | 2018 |
| Blockbuster Development Limited | Loughborough | 2021 |
| Blockchain Crowd Limited | Exeter | 2026 |
| Blockcheck Limited | Richmond Upon Thames | 2020 |
| Blockera Ltd | Liverpool | 2023 |
| Blockfoil Group Ltd | Manchester | 1980 |
| Blockgain Ltd | Manchester | 2024 |
| Blockmaester Limited | Chelmsford | 2024 |
| Blocks and Bricks Limited | Bexhill On Sea | 2023 |
| Blockscope Resident Management Limited | London | 1986 |
| Blofield Surgery Healthcare Limited | Norwich | 2003 |
| Blokk Concepts Limited | Carlisle | 2017 |
| Blommenholm Mensendieck-Institutt Limited | London | 2010 |
| Blond Design Ltd | Bolton | 2011 |
| BLOND1E Limited | Harrogate | 2020 |
| Blondette Properties Limited | Crewe | 2022 |
| Blood Iron Ltd | London | 2025 |
| Bloodwise Ltd | London | 2022 |
| Bloody London Limited | London | 2012 |
| Bloom Accounting Limited | Leicester | 2021 |
| Bloom Aesthetics and Health Care Limited | Manchester | 2025 |
| Bloom Room Studio Ltd | Crawley | 2015 |
| Bloomchem International Trading Co., Limited | Stafford | 2014 |
| Bloomfield Botanicals Ltd | Bath | 2024 |
| Bloomfield Business Ltd | Kingsbridge | 2023 |
| Bloomfield Installations Ltd | London | 2026 |
| Bloomfield Manor Management Company Limited | Bangor | 1999 |
| Bloomfields Holdings Limited | Worksop | 2017 |