| Black Barn Motor Works Ltd | Wholesale & retail | 2026 |
| Black Bull (York) Limited | Hospitality | 2010 |
| Black Bull Group UK Limited | Administrative & support | 2015 |
| Black Cat Consulting Limited | Professional & scientific | 1998 |
| Black Cat Prints Limited | Manufacturing | 2022 |
| Black Cat Property Investments Ltd | Real estate | 2021 |
| Black Cherry Alpacas Ltd | Agriculture & fishing | 2023 |
| Black Diamond Software Limited | Information & communication | 1994 |
| Black Dog Holiday Lets Limited | Real estate | 2024 |
| Black Eden Limited | Wholesale & retail | 2017 |
| Black Edge Consulting Limited | Professional & scientific | 2011 |
| Black Edge Limited | Extraterritorial | 2015 |
| Black Key Lettings Limited | Real estate | 2025 |
| Black Loch Group Limited | Real estate | 2024 |
| Black Oak Farm Limited | Manufacturing | 2026 |
| Black REX Holdings Limited | Financial services | 2026 |
| Black Smoke York Ltd | Hospitality | 2025 |
| Black Swan Digital Ltd | Information & communication | 2023 |
| Black Umbrella Holdings Ltd | Financial services | 2020 |
| Blackberry Close (York) Management Company Ltd | Real estate | 2026 |
| Blackberry Housing Ltd | Real estate | 2022 |
| Blackden Kirk Limited | Information & communication | 2024 |
| Blacker Events Ltd | Administrative & support | 2024 |
| Blacker Group Ltd | Financial services | 2026 |
| Blacker Homes Ltd | Real estate | 2025 |
| Blacker Steel Fabrications Limited | Manufacturing | 2003 |
| Blackerpadel Holdings Ltd | Financial services | 2026 |
| Blackerpadel Ltd | Construction | 2025 |
| Blackington Moorby Limited | Professional & scientific | 2025 |
| Blacks Property Consultants Limited | Real estate | 2008 |
| Blacksmiths Arms Naburn Ltd | Hospitality | 2025 |
| Blacksmiths Garage Ltd | Wholesale & retail | 2018 |
| Blackspot Distribution Ltd | Wholesale & retail | 2021 |
| Blackspot Group Ltd | Wholesale & retail | 2024 |
| Blackspot Rural Networks LLP | | 2020 |
| Blackthorn Construction Ltd | Construction | 2026 |
| Blackthorn Training & Consultancy Ltd | Education | 2010 |
| Blackveil Digital Ltd | Information & communication | 2026 |
| Blackwater International Ltd | Other services | 2019 |
| Blackwell and Denton FM Ltd | Wholesale & retail | 2022 |
| Blackwood Gate Limited | Professional & scientific | 2020 |
| Blackwulf Ltd | Transport & logistics | 2025 |
| Blaise Medical Ltd | Health & social care | 2020 |
| Blak Bear Barbers Limited | Other services | 2018 |
| Blak Bear Selby Ltd | Other services | 2021 |
| Blak Property Management Ltd | Real estate | 2020 |
| Blake House Holdings Limited | Financial services | 2020 |
| Blake House York Ltd | Real estate | 2018 |
| Blake House York Two Ltd | Real estate | 2018 |
| Blake Mews Management Company Limited | Households | 2007 |
| Blake-James Urology Ltd | Health & social care | 2019 |
| Blakeney Place Limited | Households | 1982 |
| Blakeway Milner Ltd | Professional & scientific | 2024 |
| Blandsco Holdings Limited | Real estate | 2025 |
| Blandsco Limited | Financial services | 2019 |
| Blank Social Co Ltd | Professional & scientific | 2025 |
| Blaven Change Management Limited | Information & communication | 2012 |
| Blayds House Easingwold Limited | Households | 1997 |
| BLB Management Ltd | Administrative & support | 2023 |
| Blelham Limited | Financial services | 2019 |
| Blend.Hairdressing Ltd | Other services | 2024 |
| Blendé Hair Limited | Other services | 2025 |
| Blenk Engineering Limited | Wholesale & retail | 2011 |
| Blenkin & Co Limited | Real estate | 2002 |
| BLG Plumbing & Heating Services Ltd | Construction | 2024 |
| Blija Ltd. | Health & social care | 2009 |
| Blinch (UK) Limited | Public administration | 2010 |
| Blind Image Limited | Wholesale & retail | 2019 |
| Blind Lane Land Ltd | Real estate | 2019 |
| Blink Bar Ltd | Other services | 2019 |
| Blinki Limited | Information & communication | 2023 |
| Blinova Heritage Limited | Wholesale & retail | 2025 |
| Blitz Commercial Cleaning Services Limited | Administrative & support | 2019 |
| Blizzard Property Consultants LLP | | 2018 |
| Blmd Ltd | Professional & scientific | 2013 |
| Blobbins Ltd | Financial services | 2025 |
| Bloom Bar Studio Ltd | Wholesale & retail | 2020 |
| Bloom Farming Limited | Agriculture & fishing | 2023 |
| Bloom Holdco Limited | Real estate | 2022 |
| Bloominater Ltd | Administrative & support | 2022 |
| Bloomsbury Consulting Services Limited | Professional & scientific | 1998 |
| Bloomstrade Ltd | Wholesale & retail | 2025 |
| Blossom & Wild Florals Ltd | Information & communication | 2012 |
| Blossom Coffee York Ltd. | Hospitality | 2019 |
| Blossom Cosmetic Clinic Limited | Health & social care | 2020 |
| Blossom Dental Care Limited | Health & social care | 2009 |
| Blossom Developments Ltd | Real estate | 2023 |
| Blossom Street Apartments Ltd | Households | 2025 |
| Blow (York) Limited | Other services | 2013 |
| BLS Engineering Ltd | Manufacturing | 2011 |
| BLS Stay Compliant Limited | Information & communication | 2014 |
| Blue Angel Limited | Arts & recreation | 1982 |
| Blue Base Developments Limited | Construction | 2022 |
| Blue Bobbin Ltd | Real estate | 2023 |
| Blue Box Productions Ltd | Arts & recreation | 2017 |
| Blue Box Storage (Hull) Limited | Transport & logistics | 2024 |
| Blue Consultancy 1 Ltd | Administrative & support | 2018 |
| Blue Coyote Consulting Ltd | Professional & scientific | 2023 |
| Blue Dragon Artwork Ltd | Arts & recreation | 2022 |
| Blue FLY (York) Limited | Hospitality | 2004 |