| Big-In Carpentry Limited | Construction | 2012 |
| Bilal Corporation Ltd | Wholesale & retail | 2025 |
| Bips Estates Limited | Real estate | 2017 |
| Birch Construction Surrey Ltd | Construction | 2018 |
| Birdhurst (Croydon) Limited | Real estate | 2009 |
| Birdhurst Hill Limited | Real estate | 2021 |
| Birdhurst Lawn Tennis Club Limited(The) | Arts & recreation | 1921 |
| Birdhurst Tower Residents Limited | Households | 2005 |
| Bisliz Grace Ltd | Real estate | 2024 |
| Bitterdwarf Limited | Professional & scientific | 2018 |
| Biztribe Limited | Information & communication | 2025 |
| Bjcompany Ltd | Wholesale & retail | 2025 |
| BJJ Network Ltd | Arts & recreation | 2025 |
| BKC Intl Ltd | Manufacturing | 2025 |
| Black Excellence Grads LP | | 2018 |
| Black Grape Marketing Limited | Administrative & support | 2018 |
| Black Knight Asset Management Limited | Real estate | 2015 |
| Black Knight Media Limited | Information & communication | 2010 |
| Black Pearl Dental Laboratory Ltd | Manufacturing | 2023 |
| Black Stone Construction, Trading & Consultancy Ltd | Construction | 2019 |
| Black Stone Developments and Real Estate Ltd | Real estate | 2024 |
| Blackcat Capital Ltd | Real estate | 2025 |
| Blackfinch Solutions Ltd | Information & communication | 2013 |
| Blackrose Kapital Limited | Manufacturing | 2025 |
| Blaw Training Limited | Arts & recreation | 2018 |
| Blend Properties LLP | | 2017 |
| Blenheim RTM Company Limited | Households | 2011 |
| Blewdor Limited | Real estate | 2016 |
| BLM Electrical Limited | Construction | 2018 |
| Bloo Flame Limited | Construction | 2024 |
| Blue Chip Business Travel Ltd | Administrative & support | 2024 |
| Blue Electrical London Limited | Construction | 2022 |
| Blue Monkey Consulting Limited | Health & social care | 2008 |
| Blue Monkey Health Limited | Health & social care | 2024 |
| Blue Sparrow Ltd | Extraterritorial | 2011 |
| Bluebell Building Group Ltd | Administrative & support | 2017 |
| Bluebells Hair Boutique Limited | Wholesale & retail | 2018 |
| Bluelake Investments Limited | Real estate | 2001 |
| Bluestone Group Limited | Real estate | 2015 |
| BM Tourism & Event Limited | Other services | 2015 |
| BMV Concept Ltd. | Construction | 2012 |
| Bnsr Limited | Real estate | 2024 |
| Boakye & Sons Courier Ltd | Transport & logistics | 2025 |
| Boam Digital Ltd | Information & communication | 2018 |
| Boho Partnership Limited | Other services | 2016 |
| Boldero Capital Ltd | Professional & scientific | 2011 |
| Bonfim Import Limited | Wholesale & retail | 2025 |
| Bonnington Commercial Property Consultants Limited | Real estate | 2011 |
| Bonsheca Ltd | Wholesale & retail | 2022 |
| Boomsessfit Ltd | Manufacturing | 2019 |
| Botim LP | | 2023 |
| Boulden Properties Limited | Real estate | 2020 |
| Bourne Sports Academy Ltd | Education | 2023 |
| Box Partnership Ltd | Real estate | 2022 |
| Boxford Close Management Company Limited | Households | 2018 |
| Boxstar Promotion Limited | Professional & scientific | 2024 |
| Bozoglu 92 Limited | Other services | 2019 |
| BPO Recruit Limited | Administrative & support | 2010 |
| Brady Build & Design Limited | Construction | 2026 |
| Braine Holdings Limited | Real estate | 2020 |
| Branded by Icon Limited | Wholesale & retail | 2020 |
| Brave Hearts Academy CIC | Arts & recreation | 2024 |
| Break Boundaries Limited | Administrative & support | 2011 |
| Brecknock Road Management Limited | Households | 1986 |
| Brenda Michelle Weeks Limited | Extraterritorial | 2025 |
| Brian Green Media Limited | Professional & scientific | 2003 |
| Brick Jackets Limited | Manufacturing | 2011 |
| Brick on Brick Construction Limited | Construction | 2026 |
| Bridge Cafe (Shortlands) Limited | Hospitality | 2018 |
| Bridgestock Childrens Home Ltd | Health & social care | 2026 |
| Briefs Law Limited | Professional & scientific | 2012 |
| Bright Futures 4 ALL C.I.C. | Education | 2015 |
| Brighter Future ABA Ltd | Other services | 2019 |
| Brighton Road Morley's Ltd | Hospitality | 2024 |
| Brilliantly Imperfect Ltd | Professional & scientific | 2022 |
| Brisk Aviation Ltd | Other services | 2014 |
| Brisk Group Ltd | Manufacturing | 2020 |
| Britannica VIP Services Ltd | Other services | 2023 |
| Brite-N-Breezy Limited | Administrative & support | 2006 |
| Brix Property Solutions Ltd | Construction | 2020 |
| Brixton Central Stop Limited | Wholesale & retail | 2007 |
| Brompton Housing Ltd | Real estate | 2024 |
| Brooker Laboratories Ltd | Health & social care | 2013 |
| Broth & More Co Ltd | Wholesale & retail | 2019 |
| Brothers 68 Ltd | Hospitality | 2026 |
| Brothers Business Solutions Ltd | Administrative & support | 2012 |
| Brownknights Property Management Ltd | Real estate | 2018 |
| Bryan S Ryan Limited | Administrative & support | 2013 |
| Bryant International Homes Limited | Professional & scientific | 2018 |
| Bryant Partnership Solutions Ltd | Administrative & support | 2024 |
| Bslteach Limited | Education | 2026 |
| Btrix Construction Ltd | Construction | 2025 |
| Build Future Development Limited | Construction | 2025 |
| Buildsurv Consult Limited | Professional & scientific | 2012 |
| Buildwright Properties Limited | Construction | 1992 |
| Built by Bomi Ltd | Education | 2022 |
| Buksh Enterprise LLP | | 2023 |
| Bultras Ltd | Construction | 2015 |
| Bunni Studio Ltd | Professional & scientific | 2020 |
| Bunny's (Dorset) Limited | Hospitality | 2016 |