| Bella Jade Ltd | Hospitality | 2025 |
| Bellame Contracts Limited | Construction | 2015 |
| Bellame Investments Ltd | Real estate | 2024 |
| Bellarosecare (BRC) Ltd | Health & social care | 2022 |
| Bellegrove Garage Limited | Wholesale & retail | 2021 |
| Bendito Destino Limited | Financial services | 2021 |
| Bendmore Services Limited | Transport & logistics | 2023 |
| Benihurst Limited | Construction | 2007 |
| Benine Limited | Transport & logistics | 2020 |
| Benvenuti Belle House Ltd | Hospitality | 2022 |
| Bequant Servicing Ltd | Other services | 2018 |
| Bercem Ltd | Hospitality | 2019 |
| Berry JAY Limited | Professional & scientific | 2017 |
| Besimcho Limited | Extraterritorial | 2014 |
| Bespoke Furnishings(Uk) Ltd | Wholesale & retail | 2016 |
| Bespoke'Ocity Ltd | Wholesale & retail | 2021 |
| Best British Fish & Chips Ltd | Hospitality | 2019 |
| Best Interior Designs Limited | Wholesale & retail | 2025 |
| Best London Lofts & Extensions Ltd | Construction | 2023 |
| Best London Lofts Ltd | Construction | 2015 |
| Best Windows Ltd | Manufacturing | 2026 |
| Bestamos Consultancy Ltd | Professional & scientific | 2023 |
| Bestbuild&Co Ltd | Construction | 2017 |
| Bestpoke Ltd | Construction | 2014 |
| Beta UOM Ltd | Real estate | 2018 |
| Betabets.Io Ltd | Information & communication | 2024 |
| Betivo Limited | Construction | 2012 |
| Better Living Property Developers Ltd | Construction | 2020 |
| Better Software Design Ltd | Information & communication | 2013 |
| Bexley Healthcare Services Limited | Health & social care | 2005 |
| Beyond Leisure Group Limited | Arts & recreation | 2022 |
| Beyou Together Ltd | Administrative & support | 2017 |
| Bhairab Ltd | Hospitality | 2024 |
| Bhavya Limited | Real estate | 2026 |
| BHB Construction Limited | Construction | 2025 |
| Biaf Heathcare Services and Consulting Ltd | Administrative & support | 2026 |
| Bialystock & Bloom Productions Limited | Information & communication | 1980 |
| Bibis Engineering Limited | Manufacturing | 2021 |
| Bici Construction Ltd | Other services | 2015 |
| Bickley Street Freehold Limited | Households | 2021 |
| Big BIT Solutions Ltd | Information & communication | 2015 |
| Big Business Limited | Wholesale & retail | 2018 |
| Big Deal Limited | Information & communication | 2008 |
| Big Dragon Ltd | Hospitality | 2010 |
| Big MO Ltd | Transport & logistics | 2016 |
| Bigger Business Limited | Information & communication | 2021 |
| BIH Construction Ltd | Construction | 2020 |
| Bilal Education Limited | Education | 2008 |
| Bilingual Solutions Limited | Administrative & support | 2015 |
| Bimmer Limited | Wholesale & retail | 2018 |
| Binaryreform Limited | Information & communication | 2017 |
| Binayah Capital Ltd | Professional & scientific | 2015 |
| Biorfe Ltd | Wholesale & retail | 2023 |
| Biosysion Ltd | Professional & scientific | 2024 |
| Birchwood Advisory Limited | Professional & scientific | 2018 |
| Birdwalk Ltd | Real estate | 2023 |
| Bishop Integrated Healthcare Ltd | Health & social care | 2021 |
| Bismuth Blue Limited | Information & communication | 2025 |
| Bite ME Film Catering Ltd | Hospitality | 2023 |
| Bixx Limited | Financial services | 2020 |
| Bixx Tech Limited | Information & communication | 2020 |
| Bizi ENT Ltd | Arts & recreation | 2025 |
| BJE London Limited | Administrative & support | 2004 |
| Bkwk Holdings Limited | Real estate | 2026 |
| Black & White Music Limited | Administrative & support | 2010 |
| Black Dog Press Limited | Information & communication | 2018 |
| Black Joy Presents Ltd | Arts & recreation | 2024 |
| Black Onyx Investment Group Ltd | Financial services | 2025 |
| Black Onyx Investments Ltd | Real estate | 2025 |
| Black Opal Travel Group Limited | Administrative & support | 2018 |
| Blackjack Strategy Consulting Limited | Professional & scientific | 2016 |
| Blake Builders Limited | Construction | 1998 |
| Blakron Holdings Limited | Financial services | 2025 |
| Blakron Limited | Real estate | 2017 |
| Blank Space London Ltd | Real estate | 2021 |
| BLB Electrical Limited | Construction | 2012 |
| Blenheim Realty (Home Counties) Ltd | Real estate | 2019 |
| Blissful Food Ltd | Hospitality | 2023 |
| BLL Property Investments Limited | Real estate | 2021 |
| Block 6 Castellain Mansions Freehold Limited | Real estate | 2014 |
| Block 6 Castellain Mansions RTM Co Limited | Real estate | 2015 |
| Block Cleaning Limited | Administrative & support | 2011 |
| Block Management Group Ltd | Real estate | 2025 |
| Blocks Construction Limited | Construction | 2021 |
| Bloom Beyond Properties Ltd | Real estate | 2026 |
| Bloomhale Limited | Wholesale & retail | 2018 |
| Bloomin Lovely Fencing and Garden Services Limited | Administrative & support | 2012 |
| Bloomin Lovely Fencing and Landscaping Limited | Administrative & support | 2023 |
| Bloomsalon Ltd | Other services | 2023 |
| Bloomsbury Outsourcing Limited | Extraterritorial | 2012 |
| Blossom and Bloom Salon Ltd | Other services | 2025 |
| Blossom Nurturing Nests Ltd | Health & social care | 2025 |
| Blossoms Childcare Limited | Education | 2015 |
| Bloxxit Studios Ltd | Information & communication | 2019 |
| BLP Holdings Ltd | Real estate | 2018 |
| Blue BOY Investments Ltd | Real estate | 2016 |
| Blue Leaf Enterprises Ltd | Administrative & support | 2014 |
| Blue Lion Properties Ltd | Real estate | 2003 |
| Blue Rose Ventures Ltd | Financial services | 2022 |
| BLUE7 Home Services Ltd | Households | 2026 |