| Avanda Leisure Ltd | Manufacturing | 2025 |
| Avansce Limited | Professional & scientific | 2016 |
| Avela Care Limited | Health & social care | 2025 |
| Aventurine Homes Ltd | Real estate | 2025 |
| Aventurine Properties Ltd | Real estate | 2025 |
| Avns (NE) Ltd | Construction | 2020 |
| Awesome Bars Ltd | Hospitality | 2021 |
| Awesome Leisure Ltd | Administrative & support | 2019 |
| Awesome Pubs Limited | Hospitality | 2025 |
| Awkward Wolf Studios Limited | Information & communication | 2023 |
| Axonyx Ltd | Professional & scientific | 2024 |
| AYE BEE Consultancy Ltd | Construction | 2024 |
| Ayed Ltd | Manufacturing | 2020 |
| Ayre Heating & Plumbing Limited | Construction | 2010 |
| Aysgarth 129 Limited | Real estate | 2022 |
| B & a Mini Digger Hire Limited | Construction | 2011 |
| B & C Roofing and Cladding Ltd | Construction | 2018 |
| B & F Complete Property Services Limited | Construction | 2007 |
| B a Motorhome Hire Ltd | Administrative & support | 2021 |
| B and C Roofing and Facades Ltd | Construction | 2024 |
| B Robinson Roofing & Cladding Ltd | Construction | 2022 |
| B&B International Services Ltd | Manufacturing | 2021 |
| B&C TAN Boutique Limited | Other services | 2023 |
| B. Portwood & Company Limited | Financial services | 1963 |
| B.A.G. (N/E) Limited | Financial services | 2011 |
| Babek International Ltd | Manufacturing | 2023 |
| Baby and Toddler Kingdom Limited | Wholesale & retail | 2016 |
| BAC Bulk Haulage Limited | Transport & logistics | 1998 |
| Baccanalia for Culture CIC | Arts & recreation | 2023 |
| Bailey Concrete Pumping Limited | Construction | 2001 |
| Baillie Communications Ltd | Information & communication | 2018 |
| Baillie Highways Ltd | Construction | 2025 |
| Baker Holdings NE Limited | Financial services | 2025 |
| Baker's Oven Ltd | Wholesale & retail | 2018 |
| Baller Prizes Limited | Other services | 2020 |
| Ballindullagh Barn Holiday Accommodation Limited | Hospitality | 2022 |
| Balsan Aromatherapy Limited | Wholesale & retail | 1997 |
| Bamboo Supply Limited | Wholesale & retail | 2023 |
| Barents Sea Fish Limited | Extraterritorial | 2015 |
| Barkinmad Studios Ltd | Administrative & support | 2017 |
| Barley Folde Management Company Limited | Households | 2018 |
| Barraco Pizzeria Limited | Hospitality | 2021 |
| Barrier Renewables Limited | Real estate | 2026 |
| Barrington Court Limited | Households | 2006 |
| Barrington Estates Limited | Construction | 1987 |
| Barrington Homes Limited | Construction | 1999 |
| Barrington Law Partnership LLP | | 2012 |
| Barrington Mortgage Solutions Ltd | Financial services | 2020 |
| Barron Digital Limited | Professional & scientific | 2011 |
| Barzan NE Ltd | Other services | 2026 |
| Basis Football Coaching County Durham Ltd | Arts & recreation | 2024 |
| Bath and Body Base Ltd | Administrative & support | 2024 |
| Bathroom Worlds DOT COM Ltd | Wholesale & retail | 2020 |
| Batson Construction Ltd | Construction | 2014 |
| Batson Construction Services Ltd. | Construction | 2019 |
| Batson Electrical Contractors Limited | Construction | 2006 |
| Baxter Crushers Limited | Extraterritorial | 1992 |
| Bay Horse Medical Services Ltd | Health & social care | 2023 |
| BC Timber Framers Ltd | Construction | 2022 |
| BDK Plant Hire Limited | Agriculture & fishing | 2013 |
| Bearing Sales and Purchase Limited | Administrative & support | 2023 |
| Beary Good Games Ltd | Information & communication | 2024 |
| Beautiful Island of Taiwan Limited | Hospitality | 2026 |
| Beautiful Vinyl Ltd | Wholesale & retail | 2026 |
| Beauty by KC Aesthetics Ltd | Other services | 2024 |
| Beckett Clinical Solutions (BCS) Limited | Administrative & support | 2011 |
| Bedfords Appliance Care Limited | Wholesale & retail | 2003 |
| Beedle's Limited | Hospitality | 1979 |
| Beeforth Holdings Ltd | Professional & scientific | 2023 |
| Bella Pizzeria (NE) Ltd | Hospitality | 2025 |
| Bella's Blooms Limited | Wholesale & retail | 2020 |
| Belle VUE (Doncaster) Management Company Limited | Households | 2016 |
| Belvedere Lets Ltd | Real estate | 2023 |
| Belvedere Properties (BA) Limited | Real estate | 2020 |
| BEN Coverdale Property Services Ltd | Financial services | 2024 |
| Benru Civils Ltd | Construction | 2024 |
| Berry Farm Bakery Ltd | Manufacturing | 2026 |
| Bespoak Ltd | Wholesale & retail | 2017 |
| Bespoke Architectural Fabrications Ltd | Manufacturing | 2020 |
| Best's Sports Bar Ltd | Hospitality | 2024 |
| Bettyconn Limited | Health & social care | 2025 |
| Beyond the Breed Limited | Education | 2024 |
| BFW Estates Ltd | Real estate | 2026 |
| Bigto Limited | Professional & scientific | 2009 |
| Billiat Ltd | Real estate | 2022 |
| Billy & Elaine Moloney Ltd | Professional & scientific | 2011 |
| Binchester ARC Accident Repair Centre Ltd | Wholesale & retail | 2019 |
| Binchester Enterprises Community Interest Company | Agriculture & fishing | 2018 |
| Biogas Management Services Ltd. | Other services | 2014 |
| Biographie Atelier Ltd | Wholesale & retail | 2025 |
| Birchco Ltd | Real estate | 2019 |
| Birtley Farm Services Limited | Wholesale & retail | 2011 |
| Bishi-Tech Motors Ltd | Wholesale & retail | 2022 |
| Bishop Auckland Car Wash Ltd | Administrative & support | 2019 |
| Bishop Auckland Community Events CIC | Administrative & support | 2024 |
| Bishop Auckland Community Partnership | Professional & scientific | 2002 |
| Bishop Auckland Development Company Limited | Administrative & support | 2013 |
| Bishop Auckland Farriers Limited | Agriculture & fishing | 2014 |
| Bishop Auckland Football Club Limited | Arts & recreation | 1997 |
| Bishop Auckland Glazing Co. Limited | Construction | 1986 |