| Border Offset Limited | Manufacturing | 1979 |
| Border Plumbing Services Ltd | Construction | 2017 |
| Border Property Lettings Limited | Extraterritorial | 2012 |
| Border Racquets Limited | Wholesale & retail | 2020 |
| Border Rythm Ltd | Arts & recreation | 2019 |
| Border Show Services Group Limited | Extraterritorial | 2021 |
| Border Sports Services Ltd | Wholesale & retail | 2002 |
| Border Stone Quarries Limited | Mining & quarrying | 2010 |
| Border Storage Limited | Other services | 1995 |
| Border Taxis Carlisle Ltd | Transport & logistics | 2025 |
| Border Trader Ltd | Wholesale & retail | 2025 |
| Border Trucks Ltd. | Administrative & support | 2003 |
| Border Vans Limited | Transport & logistics | 2006 |
| Border Ventures Limited | Extraterritorial | 2004 |
| Border Websites Limited | Information & communication | 2000 |
| Borderbrite Limited | Administrative & support | 2003 |
| Borderbrite Window Cleaning Limited | Administrative & support | 2014 |
| Bordercolour Limited | | 1981 |
| Borderlands Leisure Ltd | Wholesale & retail | 2021 |
| Borderlines Festival CIC | Arts & recreation | 2021 |
| Borderloos Limited | Extraterritorial | 2021 |
| Borderway Finance Limited | Financial services | 1995 |
| Borthwick Contracts Ltd | Construction | 2024 |
| BOS Glazing Ltd | Construction | 2018 |
| Boss Deliveries Ltd | Transport & logistics | 2018 |
| Botanic Room Ltd | Hospitality | 2025 |
| Botcherby Community Association | Other services | 2003 |
| Botchergate Foods Ltd | Hospitality | 2026 |
| Boundary Layer Aviation Ltd | Professional & scientific | 2026 |
| Bounty Properties Services Ltd | Financial services | 2024 |
| BOW Farms Limited | Agriculture & fishing | 2008 |
| Bowman Forecourt Services Limited | Manufacturing | 2014 |
| Bowman Property Group Limited | Real estate | 2025 |
| Box Arena Bites Ltd | Hospitality | 2026 |
| Boyd Hair and Beauty Carlisle Limited | Other services | 2020 |
| Boyle Management & Security Ltd | Professional & scientific | 2014 |
| Bpff (Carlisle) Limited | Hospitality | 2010 |
| BPH Site Services Ltd | Construction | 2024 |
| BPK Estate Agents Limited | Real estate | 2007 |
| BQ Heating and Plumbing Ltd | Construction | 2017 |
| BQ Heating Limited | Construction | 2022 |
| Braeburn Properties Limited | Real estate | 1961 |
| Bramble Nook Construction Limited | Construction | 2018 |
| Brampton & Border Hospitality Ltd | Hospitality | 2026 |
| Brampton Electrical Services (Cumbria) Ltd | Construction | 2021 |
| Brampton Golf Club (Trading) Ltd | Arts & recreation | 2016 |
| Brampton Laundry Ladies Limited | Administrative & support | 2024 |
| Brampton Pallets Limited | Professional & scientific | 2010 |
| Brampton Pharmacy Limited | Wholesale & retail | 2014 |
| Brampton Skip Hire Limited | Water & waste | 1999 |
| Brand New Living Ltd | Real estate | 2019 |
| Brand NU @ Limited | Construction | 2019 |
| Brandal Home Investments Limited | Real estate | 2020 |
| Brandal Homes Limited | Construction | 2023 |
| Brandfern Ltd | Construction | 2025 |
| Brandhouzz Ltd | Professional & scientific | 2021 |
| Branding Ants Ltd | Professional & scientific | 2020 |
| Brantwood Holdings (Cumbria) Ltd | Financial services | 2022 |
| Brantwood Property (Cumbria) Ltd | Real estate | 2024 |
| Brassford Ltd | Real estate | 2025 |
| Bravado Maintenance Ltd | Construction | 2023 |
| Braveologist Ltd | Administrative & support | 2022 |
| Brayton Engineering Limited | Manufacturing | 2003 |
| Brayton Lakeside Lodges Limited | Extraterritorial | 2012 |
| Bread & Banter Limited | Hospitality | 2025 |
| Brian Carson Building Contractors Limited | Construction | 2003 |
| Brian Hetherington Limited | Construction | 2000 |
| Brick and Stone Solutions Limited | Wholesale & retail | 2021 |
| Brick in the Wall Ltd | Real estate | 2019 |
| Bricksinbloom Ltd | Wholesale & retail | 2020 |
| Brickstationuk Community Interest Company | Hospitality | 2022 |
| Bridge Mills (Property) LLP | | 2009 |
| Brierdene (Backworth Park) Management Company Limited | Households | 2016 |
| Briggs Construction Limited | Construction | 1998 |
| Briggs Homes Limited | Construction | 2004 |
| Briggslogistics Ltd | Transport & logistics | 2025 |
| Brigsteer Rise (Kendal) Management Company Limited | Real estate | 2022 |
| Brisco Road Management Limited | Households | 1989 |
| British Rouge DE L'Ouest Sheep Society | Agriculture & fishing | 1987 |
| British Vendeen Sheep Society Limited | Other services | 1982 |
| Broadacres Property Ltd | Real estate | 2020 |
| Broadfield and Company Limited | Energy | 2014 |
| Broadway Care Solutions Ltd | Health & social care | 2023 |
| Broadway Farms North | Construction | 2024 |
| Brockley Management Company Limited | Real estate | 2018 |
| Brogan Thompson Photography Ltd | Professional & scientific | 2021 |
| Brook Worthy Law Ltd | Professional & scientific | 2014 |
| Brookwood Park (Kirkham) Management Company Limited | Households | 2015 |
| Broom Farm Holdings Ltd | Real estate | 2025 |
| Brougham Fields (Carleton) Management Company Limited | Real estate | 2020 |
| Brown Bear Creative Ltd | Arts & recreation | 2015 |
| Brown Consultancy Limited | Education | 2025 |
| Brown Dent Farming Company Ltd | Agriculture & fishing | 2023 |
| Brown Hair Limited | Other services | 2010 |
| Brown Rice Farms Limited | Financial services | 2024 |
| Brown Rice Property Limited | Real estate | 2022 |
| Brown's Welding & Fabrication Limited | Construction | 2005 |
| Brownber Limited | Hospitality | 2016 |
| Brownrigg Developments Limited | Administrative & support | 1999 |
| Brownrigg Properties Limited | Financial services | 2011 |