| Blacknight Records Limited | Extraterritorial | 2002 |
| Blacksmiths Arms Ashford Limited | Hospitality | 2026 |
| Blackstone Printing Ltd. | Information & communication | 2017 |
| Blackstone Recruitment Limited | Administrative & support | 2018 |
| Blackwood Capital Ltd | Extraterritorial | 2025 |
| Blades of Gold Barbers Ltd | Other services | 2020 |
| Blagovest Kovachki Ltd | Transport & logistics | 2015 |
| Blaise Renewables Limited | Water & waste | 2018 |
| Blawith Road NO 1 Limited | Households | 2006 |
| Blaydon Enterprises Ltd | Energy | 2024 |
| Ble's Love Cakes Ltd | Manufacturing | 2025 |
| Blended by Chan Conway Limited | Other services | 2023 |
| Blended Learning Studio UK Ltd | Professional & scientific | 2017 |
| Blenhope Investments Limited | Construction | 1960 |
| Bliby Advisory (Compliance) LLP | | 2012 |
| Bliby Bespoke Ltd | Manufacturing | 2024 |
| Bliby Compliance & Training LLP | | 2015 |
| Bliby Investments Limited | Manufacturing | 1997 |
| Bliby Plastics Limited | Manufacturing | 2000 |
| Blink Machine Ltd | Information & communication | 2020 |
| Blinken Ltd | Professional & scientific | 2021 |
| Blooming Beans Ltd | Hospitality | 2023 |
| Blossom & Flower Power Ltd | Professional & scientific | 2021 |
| Blossom Accountancy Ltd | Professional & scientific | 2023 |
| Blossom Forever Ltd | Other services | 2016 |
| Blossom Law Solicitors LLP | | 2011 |
| Blossoms Baby Limited | Health & social care | 2019 |
| Blossoms Hair and Beauty Limited | Administrative & support | 2011 |
| Blossoms UK Trading Ltd | Health & social care | 2025 |
| BLR Transport Ltd | Transport & logistics | 2025 |
| BLU Donkey Multi Media Services Ltd | Construction | 2023 |
| Blue Book Creative Ltd | Administrative & support | 2017 |
| Blue Chilli Microsystems Limited | Information & communication | 2002 |
| Blue Goose Exploration Ltd | Professional & scientific | 2020 |
| Blue Lace Events Ltd | Wholesale & retail | 2024 |
| Blue Lettings Limited | Real estate | 2017 |
| Blue Lettings Partnership LLP | | 2022 |
| Blue Mushroom Digital Ltd | Manufacturing | 2019 |
| Blue ORB Productions Limited | Information & communication | 2018 |
| Blue PIG Cleaning Ltd | Administrative & support | 2021 |
| Blue Portico Ltd | Administrative & support | 2026 |
| Blue RAM, Lease and Brokerage Limited | Professional & scientific | 2011 |
| Blue Shop Ashford Ltd | Wholesale & retail | 2024 |
| Blue Sky Creative Limited | Information & communication | 2008 |
| Blue Stone Care Limited | Health & social care | 2026 |
| Bluebay E-Commerce Limited | Households | 2015 |
| Bluebell Abodes Ltd | Real estate | 2021 |
| Bluebell Accountancy Limited | Administrative & support | 2025 |
| Bluebell Development Services (HAM Mill) Limited | Construction | 2008 |
| Bluebell Energy Ltd | Professional & scientific | 2013 |
| Bluebell Psychology Ltd | Health & social care | 2021 |
| Bluechip Review Ltd | Information & communication | 2022 |
| Blueden Healthcare Ltd | Transport & logistics | 2020 |
| Bluefin Capital Limited | Professional & scientific | 2025 |
| Bluefin Developments (Abbington) Limited | Health & social care | 2023 |
| Bluehaus Investments Limited | Real estate | 2025 |
| Bluenest Consulting Ltd | Professional & scientific | 2022 |
| Bluescore Limited | Other services | 2025 |
| Bluesky Logic Limited | Information & communication | 1999 |
| Bluetit Ltd | Real estate | 2022 |
| Bluewater Caravan Park (Hythe) Limited | Real estate | 2025 |
| Bluewater Caravan Park (Kent) Limited | Real estate | 2023 |
| Blush Nail and Beauty Lounge Ltd | Other services | 2019 |
| Blythe Electrical Ltd | Construction | 2012 |
| BM Ambulance Group Limited | Transport & logistics | 2015 |
| BM Ambulance Holdings Limited | Professional & scientific | 2023 |
| BM Building 4 YOU Ltd | Construction | 2026 |
| BM Events Planner Ltd | Hospitality | 2025 |
| BM Services Europe Limited | Professional & scientific | 2006 |
| BM Wines Limited | Wholesale & retail | 1996 |
| Bmag Limited | Health & social care | 2019 |
| BMS Global Services Ltd | Professional & scientific | 2018 |
| BMS Utilities Limited | Construction | 2025 |
| BNB Electrical Contractors Ltd | Construction | 2019 |
| Bnne Developments Ltd | Construction | 2020 |
| Bnne Property Ltd | Real estate | 2022 |
| BNZ Autos Ltd | Wholesale & retail | 2025 |
| BO Country Co Ltd | Wholesale & retail | 2025 |
| Boat on a Rope Limited | Manufacturing | 2025 |
| Bob's Legacy Ltd | Hospitality | 2015 |
| Boba and YU Ltd | Extraterritorial | 2023 |
| Bobinski Shop Ltd | Wholesale & retail | 2021 |
| Bockhanger Farms Limited | Agriculture & fishing | 1956 |
| Bodha Drinks Limited | Manufacturing | 2020 |
| Bodybronze London Ltd | Real estate | 2000 |
| Bodygold Limited | Wholesale & retail | 1995 |
| BOG Farm Limited | Agriculture & fishing | 2024 |
| Boiler on the Blink Limited | Construction | 2018 |
| Boilertime Ltd | Construction | 2024 |
| Bokar Solutions Limited | Information & communication | 2017 |
| Boldshaves Ltd | Arts & recreation | 2014 |
| Boleyn Assets Limited | Financial services | 2010 |
| Bolliger UK Limited | Transport & logistics | 2010 |
| Bolsover Consultancy Ltd | Professional & scientific | 2012 |
| Bomad Life Limited | Information & communication | 2025 |
| Bonded Cleaning & Maintenance Limited | Professional & scientific | 2017 |
| Bondforce Limited | Extraterritorial | 2007 |
| Bone Brass Limited | Hospitality | 2026 |
| Bonfleur Equestrian Ltd | Arts & recreation | 2017 |
| Bongo's Brew Ltd | Hospitality | 2026 |