| BIO Pulse Labs Ltd | Glasgow | 2025 |
| Bio-Energy Life Center London Ltd. | London | 2012 |
| Bio-F Solutions Limited | London | 2020 |
| Bio-Green Exports Limited | Grays | 2004 |
| Bio-Sustainability Limited | Heathfield | 2008 |
| Bioadam Ltd | London | 2024 |
| Bioberton Ltd | London | 2024 |
| Biobrady Ltd | London | 2024 |
| Biobridge Energy Limited | King'S Lynn | 2026 |
| Biocare (Holdings) Limited | Redditch | 2002 |
| Biocare International Limited | Redditch | 1994 |
| Biocare Waste Limited | Newmarket | 2025 |
| Biocase Ltd | Braintree | 2011 |
| Biocassie Ltd | London | 2024 |
| Biochem Limited | London | 1985 |
| Biocon Ltd | Kidderminster | 2018 |
| Biod Services Limited | London | 2001 |
| Biodiversity Land Ltd | Huntingdon | 2024 |
| Biodiversity NET Gain (BNG) Ltd | Liskeard | 2020 |
| Biodiversity NET Gain Ltd | Liskeard | 2020 |
| Biodiversity Plus | Worcester | 2010 |
| Biodiversityxchange Limited | Sedbergh | 2022 |
| Bioflow Limited | Saltash | 2017 |
| Biogen EM Midco Limited | Bedford | 2017 |
| Biogen EM Topco Limited | Bedford | 2017 |
| Biogen Holdings Limited | Bedford | 2012 |
| Biogrid Limited | Omagh | 2015 |
| Bioguardian Partners Ltd | London | 2025 |
| Bioherbs Cosmetices Group Limited | London | 2019 |
| Biohermes Diagnostics Limited | Cardiff | 2019 |
| Bioland International Co., Limited | London | 2012 |
| Biomass 4 Wales Limited | Ammanford | 2013 |
| Biomass Fuel Supplies Ltd | St. Helens | 2014 |
| Biomaster Limited | Stafford | 2003 |
| Biomedinc Ltd | Bristol | 2023 |
| BIOMEDPRINT3D Ltd | Dundee | 2021 |
| Biometric Access Control Systems Limited | Southampton | 2007 |
| Biometric Time Solutions Limited | | 2007 |
| Bionic Limited | Chislehurst | 1997 |
| Bionic Mobility Ltd | Coventry | 2016 |
| Bionic Productions Limited | Beaconsfield | 2012 |
| Bionics Limited | Buckinghamshire | 2007 |
| Bioperfect International Limited | Beckenham | 2018 |
| Biopharmaspec (UK) Limited | Weymouth | 2014 |
| Biopolis Lifesciences Private Limited | Uxbridge | 2018 |
| Biopower Solutions Ltd | Ormskirk | 2017 |
| Bioq Pharma Limited | Ilford | 2005 |
| Biorex Ltd | London | 2026 |
| Biosave Limited | Knaresborough | 2012 |
| Biosensors Ltd | Wirral | 2020 |
| Biosettle Ltd | London | 2024 |
| Biospear Limited | Halesowen | 2015 |
| Biosphere Ltd | Burgess Hill | 2006 |
| Biostrat Consultancy Limited | Bracknell | 2023 |
| Biosun Services (UK) Limited | Rainham | 2014 |
| Biotal Limited | Malvern Link | 1991 |
| Biotherm (UK) Limited | Sevenoaks | 2022 |
| Biotherm Group Limited | St. Helens | 2024 |
| Biotransitions Ltd | Norwich | 2025 |
| Bioventure Limited | Norwich | 2009 |
| Bioventure Medical Innovations Ltd | Norwich | 2012 |
| Biovet Asia Limited | London | 2025 |
| Biovista Sciences Limited | Norwich | 2008 |
| Biow Exposomics UK Ltd | Stoke-On-Trent | 2021 |
| Biowant Ltd | London | 2024 |
| Biowatt Limited | Bedford | 2012 |
| Biowide Ltd | London | 2024 |
| BIP - BOP Records Limited | London | 1981 |
| BIP Resources Limited | Middlewich | 2019 |
| Bipex Ltd | London | 2025 |
| Bira (UK) Limited | Gloucester | 2009 |
| Biran Yachting Ltd | London | 2019 |
| Birch 1969 Limited | Epping | 2013 |
| Birch Accounting Solutions Limited | Clitheroe | 2022 |
| Birch Avenue Company Limited | Cookstown | 2015 |
| Birch Brothers Limited | Bristol | 2023 |
| Birch Grove Preservation Limited | County Durham | 2006 |
| Birch Hollow Trading House Ltd | Manchester | 2026 |
| Birch House 1956 Limited | Pickering | 2014 |
| Birch Motorsport Limited | Leicester | 2025 |
| Birch Park Management Company Limited | Nottingham | 2005 |
| Birch Ridge Investment House Ltd | Manchester | 2026 |
| Birch Shadow Consulting Solutions Ltd | Manchester | 2026 |
| Birch Tree Avenue 1973 Limited | Stockport | 2014 |
| Birch Tree Company NO 5 Limited | Magherafelt | 2014 |
| Birch Tree Company NO 6 Limited | Ballymoney | 2014 |
| Birch Tree IT Ltd | Leighton Buzzard | 2016 |
| Birch's Homes Limited | Cambs | 2005 |
| Birchall Blackburn Limited | Preston | 1995 |
| Birchalls the Riding Shop Limited | Sittingbourne | 2003 |
| Birchetts 1957 Limited | Bracknell | 2015 |
| Birchfield Ventures Limited | Esher | 2016 |
| Birchmere Homes Limited | Llangollen | 2002 |
| Birchridge Limited | London | 1997 |
| Birchwood Consulting Management Services Limited | Stoke On Trent | 2009 |
| Birchwood Development Partners Ltd | London | 2011 |
| Birchwood Esher One Ltd | Weybridge | 2020 |
| Birchwood Esher Three Ltd | Weybridge | 2020 |
| Birchwood Esher Two Ltd | Weybridge | 2020 |
| Birchwood Horizon Trading Solutions Ltd | Manchester | 2026 |