| BOT Solutions 24/7 Ltd | Professional & scientific | 2024 |
| Bounty BD Ltd | Wholesale & retail | 2024 |
| Bournepad Limited | Real estate | 2020 |
| BOW Street Property Management Company Limited | Households | 2003 |
| BOW Theatre Management Limited | Households | 2001 |
| Bowendryden Limited | Wholesale & retail | 2023 |
| Bowes Airframe Ltd | Manufacturing | 2025 |
| BP Consultant Limited | Construction | 2023 |
| Bradrose Materials Procurement Ltd | Construction | 2023 |
| Bradshaw Daniel Properties Limited | Households | 2020 |
| Braeburnhill Properties Ltd | Administrative & support | 2013 |
| Brand Movements Limited | Professional & scientific | 2013 |
| Brantwych Gate Management Company Limited | Households | 1995 |
| Branx Fitness Limited | Wholesale & retail | 2008 |
| Bratton Limited | Professional & scientific | 2012 |
| Bratton Management Limited | Professional & scientific | 2014 |
| Bratton Projects Limited | Professional & scientific | 2014 |
| Bratton Technical Limited | Professional & scientific | 2014 |
| Bratton Training Limited | Education | 2014 |
| Brave New Work Limited | Professional & scientific | 2022 |
| Braywise Property Ltd | Real estate | 2022 |
| Brewery Court Limited | Households | 2020 |
| Brick Matters Limited | Wholesale & retail | 2016 |
| Bridge Management Training Limited | Professional & scientific | 1989 |
| Bridge Protocol Ltd | Information & communication | 2026 |
| Bridier Holdings Ltd | Professional & scientific | 2020 |
| Briers Farms (Steeple Morden) Limited | Agriculture & fishing | 1962 |
| Briggs & Mortimer Limited | Real estate | 2010 |
| Bright Spice Ltd | Hospitality | 2025 |
| Brighter Vision Limited | Professional & scientific | 1966 |
| Brilliant Volunteers Ltd | Administrative & support | 2026 |
| Britasia Solutions Ltd | Wholesale & retail | 2025 |
| British Aerobatic Academy Ltd | Education | 2012 |
| British Aviation Academy Ltd | Transport & logistics | 2016 |
| British Hardwood Tree Nursery Limited | Other services | 2004 |
| Briton Spin Soundworks Limited | Information & communication | 2025 |
| Brix Trade Ltd | Wholesale & retail | 2023 |
| Broadcloud Group Ltd | Information & communication | 2022 |
| Broadfield Construction Limited | Construction | 2013 |
| Broadreach Nature Ltd | Wholesale & retail | 2014 |
| Brollet Ltd | Manufacturing | 2025 |
| Bromley Wharf Limited | Manufacturing | 2010 |
| Brook Cottage Farm Riding School LLP | | 2025 |
| Brook Street East Management Co Limited | Households | 2019 |
| Brooks Ecological Ltd | Professional & scientific | 2005 |
| Brooks Removals Ltd | Transport & logistics | 2019 |
| Broomfield Courtyard (Haverhill) Management Company Limited | Real estate | 2005 |
| Brothers Building Solutions Ltd | Construction | 2023 |
| Brownfields Management Limited | Households | 1980 |
| Brownie-Points.Biz Limited | Administrative & support | 2004 |
| Bruel & Kjaer UK Limited | Manufacturing | 2000 |
| Bruel & Kjaer VTS Limited | Manufacturing | 1981 |
| Bryce Labs Ltd | Professional & scientific | 2026 |
| BTI Construction One Ltd | Construction | 2015 |
| BTI Plumbing and Heating Ltd | Construction | 2017 |
| Bubbachubs UK Ltd | Wholesale & retail | 2024 |
| Building and Fire Safety Cases Limited | Public administration | 2024 |
| Buildings Archaeology Limited | Professional & scientific | 2012 |
| Bumblebee Management Limited | Real estate | 2023 |
| Bunbury Terrace Limited | Real estate | 2011 |
| Buntingford Brewery Limited | Manufacturing | 2017 |
| Buntingford DRY Cleaners Limited | Other services | 2009 |
| Buntonhomes Ltd | Real estate | 2026 |
| Buntonproperties Ltd | Real estate | 2024 |
| Burge & Sons Builders Ltd | Construction | 2019 |
| Burnell Jones Ltd | Construction | 2021 |
| Burnham Green Farm Limited | Wholesale & retail | 2026 |
| Business and IT Limited | Information & communication | 2007 |
| Business Growers.Biz Limited | Professional & scientific | 2010 |
| Business Machines (Central) Limited | Administrative & support | 2017 |
| Butcher's House Royston Ltd | Wholesale & retail | 2023 |
| Buttercup Blossoms Limited | Households | 2020 |
| Butterfield Drive Management Company Limited | Real estate | 2011 |
| Button 17 Limited | Professional & scientific | 2022 |
| BW Electrical Services Ltd | Construction | 2021 |
| C & G Firearms Limited | Wholesale & retail | 2008 |
| C 130 Limited | Professional & scientific | 2017 |
| C B Building Services (Royston) Limited | Construction | 2017 |
| C B Designs & Project Management Ltd | Professional & scientific | 2021 |
| C D Pro-Fit Ltd | Wholesale & retail | 2004 |
| C Engelmann Limited | Real estate | 1925 |
| C G C Properties Limited | Real estate | 1988 |
| C L Travel Ltd | Transport & logistics | 2014 |
| C Paxton Building Services Limited | Construction | 2022 |
| C Swan Holdings Limited | Real estate | 2015 |
| C.J.A. Event Management Limited | Professional & scientific | 2014 |
| C21 Productions Limited | Information & communication | 2018 |
| C4B Media Limited | Professional & scientific | 2012 |
| CAD First Limited | Professional & scientific | 2009 |
| CAD Storage & Distribution Ltd | Transport & logistics | 2025 |
| CAD Technologies Limited | Manufacturing | 2014 |
| Caelum Systems Ltd | Manufacturing | 2018 |
| Cafe Amigo Ltd | Wholesale & retail | 2023 |
| Caldecote Village Institute Limited | Health & social care | 2006 |
| Calibrea Limited | Professional & scientific | 2009 |
| Caliq Software Limited | Information & communication | 1992 |
| CAM European (UK) Limited | Transport & logistics | 2009 |
| CAM Store (Royston) Ltd | Transport & logistics | 2009 |
| CAM Store Limited | Transport & logistics | 2001 |
| Cambrad Limited | Real estate | 1991 |