| Big Bear Engineering Ltd | Manufacturing | 2004 |
| Big Bite (Hull) Limited | Hospitality | 2019 |
| Big BOB Cars Sales Ltd | Wholesale & retail | 2023 |
| Big Capital Ltd | Real estate | 2025 |
| Big Gold Jewellery Limited | Wholesale & retail | 2025 |
| Biggin 1959 Limited | Extraterritorial | 2013 |
| Bilbas Holdings Limited | Financial services | 2025 |
| Bill Atkin Limited | | 1974 |
| Bill Draper Haulage Limited | Transport & logistics | 1987 |
| Billabong Construction Services Limted Limited | Construction | 2016 |
| Billda Ltd | Information & communication | 2025 |
| Billies Barbers Limited | Other services | 2011 |
| Billy the Hot TUB GUY Limited | Manufacturing | 2020 |
| Bilton Blinds Limited | Manufacturing | 2022 |
| Bind Soft Furnishings Limited | Wholesale & retail | 2019 |
| Bintin Care Ltd | Health & social care | 2025 |
| BIO2 Limited | Professional & scientific | 2026 |
| Biodata Tools Ltd | Wholesale & retail | 2023 |
| Biostrefa Ltd | Administrative & support | 2016 |
| Biovitae Life Ltd | Wholesale & retail | 2021 |
| Birch Sheet Metal Limited | Manufacturing | 1996 |
| BIRCH2 Limited | Manufacturing | 2000 |
| Birchgrove Estates Limited | Real estate | 2001 |
| Bird's Courier Services Ltd | Transport & logistics | 2025 |
| Birmex Supplies (Yorkshire) Ltd | Wholesale & retail | 2024 |
| Bishop Lane (Hull) Management Company Limited | Households | 2015 |
| Bishops Garth (Beverley) Management Company Limited | Households | 2013 |
| Bismarck Bortier Limited | Health & social care | 2005 |
| Bispol Candles Limited | Wholesale & retail | 2021 |
| Biteback Publishing Limited | Information & communication | 2009 |
| Bitofaview Limited | Professional & scientific | 2025 |
| Bitz and Bobz UK Competitions Ltd | Arts & recreation | 2025 |
| Biz-Networks Ltd | Information & communication | 2010 |
| Bizmartcart Ltd | Wholesale & retail | 2026 |
| Bizy BOY Cafe Limited | Hospitality | 2025 |
| BJ Media Ltd | Professional & scientific | 2025 |
| BJP Building & Construction Limited | Construction | 2020 |
| BJY Electrical Limited | Construction | 2022 |
| BJY Properties Limited | Real estate | 2023 |
| BKC Engineering Limited | Construction | 2017 |
| BKN2 Limited | Real estate | 2026 |
| Bktp Properties Ltd | Real estate | 2025 |
| BLA Shipping Ltd | Agriculture & fishing | 2024 |
| Black and White North Ltd | Wholesale & retail | 2021 |
| Black Coffret Limited | Wholesale & retail | 2026 |
| Black Desk Consulting Limited | Professional & scientific | 2011 |
| Black Dots Video Limited | Information & communication | 2017 |
| Black Investment Properties Ltd | Real estate | 2025 |
| Black Marlin Properties Limited | Real estate | 2013 |
| Black Plant Hire Limited | Administrative & support | 2009 |
| Black Reign Media Limited | Wholesale & retail | 2025 |
| Black Rose Studio Ltd | Information & communication | 2023 |
| Black Sea Group Ltd | Wholesale & retail | 2023 |
| Blackarts Limited | Professional & scientific | 2002 |
| Blackbean Property Company Limited | Real estate | 2021 |
| Blackbird Investments Ltd | Real estate | 2022 |
| Blackburn Leisure Limited | Hospitality | 2015 |
| Blackburn Sports and Social Community Club Limited | Hospitality | 2015 |
| Blackhood Ltd | Manufacturing | 2017 |
| Blackhorse Restaurants Ltd | Hospitality | 2018 |
| Blackie and Treasure Dickinson Limited | Manufacturing | 2003 |
| Blackoack Property Group Ltd | Real estate | 2026 |
| Blacksmiths Accommodation Limited | Hospitality | 2026 |
| Blacksmiths Coniston Limited | Hospitality | 2018 |
| Blackvale Limited | Wholesale & retail | 2026 |
| Blackvault Holdings Ltd | Professional & scientific | 2023 |
| Blade Care Solutions Ltd | Construction | 2023 |
| Blade Restore Ltd | Manufacturing | 2024 |
| Bladecoreuk Ltd | Manufacturing | 2026 |
| Blaga Limited | Construction | 2023 |
| Blake Bros.(Engineers)Limited | Wholesale & retail | 1960 |
| Blanc.Noir Ltd | Professional & scientific | 2025 |
| Blaxon Learning Solutions Limited | Professional & scientific | 2021 |
| Blessed A&O Afro Caribbean Supermarket International Ltd | Wholesale & retail | 2026 |
| Blessing and Honour Limited | Wholesale & retail | 2025 |
| Blessing SAM Cuisine Ltd | Hospitality | 2025 |
| Blessings UK Ltd | Professional & scientific | 2019 |
| Bleu Box Group Limited | Financial services | 2026 |
| Bleu Box Limited | Information & communication | 2018 |
| Bleu Squared Limited | Financial services | 2024 |
| Blinds With BLU Limited | Manufacturing | 2025 |
| BLK Glow Ltd | Households | 2026 |
| Blmn Holdings Ltd | Administrative & support | 2022 |
| Blocco Ltd | Wholesale & retail | 2025 |
| Block 1 Rank House Limited | Construction | 2025 |
| Block 2 Victoria House Limited | Construction | 2025 |
| Block 47 Investments Limited | Real estate | 2025 |
| Block 5 Clarendon House Limited | Construction | 2025 |
| Block Programming Ltd | Professional & scientific | 2025 |
| Blogwizarro Ltd | Information & communication | 2024 |
| Blok Build Ltd | Manufacturing | 2015 |
| Blok CNC Limited | Construction | 2015 |
| Blok Facade Ltd | Professional & scientific | 2018 |
| Blondes Coffee Limited | Hospitality | 2005 |
| Bloodfast EVS Ltd | Health & social care | 2007 |
| Bloom Creative Solutions Limited | Administrative & support | 2019 |
| Bloom House of Aesthetics Ltd | Other services | 2023 |
| Bloomfield Developers Ltd | Real estate | 2025 |
| Blossom Empire Ltd | Administrative & support | 2023 |
| Blossom Tree Estates Ltd | Real estate | 2026 |