| Big Big Ideas Ltd | Professional & scientific | 2024 |
| Big M Productions Limited | Information & communication | 1978 |
| Bijou Builders Limited | | 1985 |
| Birch Services Limited | Professional & scientific | 2015 |
| Bistrotheka Ltd | Wholesale & retail | 2018 |
| Blinds and Shutters Limited | | 1985 |
| Blowfish IT Services Ltd | Information & communication | 2007 |
| BLU Kangaroo Consulting Ltd | Professional & scientific | 2015 |
| Blue Mode Consulting Ltd | Professional & scientific | 2011 |
| Boland Properties Limited | Real estate | 2000 |
| Bombay Enterprise Ltd | Hospitality | 2025 |
| Bombay Pizza Global Ltd | Hospitality | 2025 |
| Booker Holdings Limited | Financial services | 2025 |
| Booker Water Retail Ltd | Water & waste | 2026 |
| Boorman Consultancy Services Limited | Wholesale & retail | 2015 |
| Bouma Consulting Ltd | Information & communication | 2011 |
| Bradbury Life Sciences Ltd | Administrative & support | 2010 |
| Branded Content Marketing Association Limited | Information & communication | 2011 |
| Braybrooks in Car Enhancements Ltd | Wholesale & retail | 2022 |
| Brickwall Property Solutions Limited | Construction | 2021 |
| Bride Hall | | 1993 |
| Briers Properties Limited | Real estate | 2026 |
| Briffa Phillips Limited | Administrative & support | 2013 |
| Brightside Digital Engagement Ltd | Professional & scientific | 2019 |
| Brittons Daycare Limited | Education | 2013 |
| Broad Reach Retail Consultancy Limited | Other services | 1999 |
| Bronwell Limited | Education | 1992 |
| Brook Court Property Management Company Limited | Real estate | 2011 |
| Brooks & Kempton Ltd | Wholesale & retail | 2012 |
| Brooks Murray Architects Ltd. | Professional & scientific | 2002 |
| Brooks Murray Properties Limited | Real estate | 2019 |
| Bryan Bishop and Partners Sales Limited | Real estate | 2021 |
| Buckden Partners Limited | Administrative & support | 2016 |
| Buckden Partners Real Estate Limited | Administrative & support | 2026 |
| Bueno 777 Limited | Financial services | 2024 |
| Bukhari Healthcare Limited | Health & social care | 2021 |
| Burgess Scientific Consulting Limited | Professional & scientific | 2019 |
| Business Boffins Limited | Professional & scientific | 2020 |
| Business Digswell Groomers Ltd | Administrative & support | 2023 |
| Business Process Excellence Limited | Professional & scientific | 2017 |
| BWS Laboratories Limited | Professional & scientific | 2022 |
| BWS Properties Limited | Real estate | 2023 |
| C a Warner Ltd | Construction | 2015 |
| C Matheson Ltd | Wholesale & retail | 2016 |
| Caas Group Limited | Administrative & support | 2024 |
| Caddington Investments Ltd | Real estate | 2024 |
| Cafe Twelve Limited | Hospitality | 2026 |
| Cain Build Ltd | Construction | 2019 |
| Cain East Ltd | Construction | 2019 |
| Calderon Tiles Limited | Wholesale & retail | 2015 |
| Cameron Kalder International Limited | Administrative & support | 2004 |
| Cancake Ltd | Administrative & support | 2016 |
| Capacity Consulting Limited | Arts & recreation | 2011 |
| Capital Carz Ltd | Wholesale & retail | 2015 |
| Captive Reality Ltd | Information & communication | 2017 |
| Care Buddy UK Ltd | Information & communication | 2016 |
| Carly Twyne Consultancy Limited | Professional & scientific | 2025 |
| Carvers Croft 24-31 Limited | Real estate | 2005 |
| Catherine's Horse Stables Ltd | Agriculture & fishing | 2021 |
| Cavaliers Studio Ltd | Professional & scientific | 2019 |
| Celtic Harmony | Education | 1998 |
| CG Accounting Limited | Professional & scientific | 2008 |
| Chater & Chater Ltd | Information & communication | 2017 |
| Childs Consulting Limited | Financial services | 2022 |
| Chiswick Security LLP | | 2022 |
| Chrys Estates Management Ltd | Real estate | 2024 |
| Chrys Group Ltd | Professional & scientific | 2024 |
| Chrys Properties Ltd | Wholesale & retail | 2016 |
| Churchfield Technology Limited | Information & communication | 2007 |
| Château Paul Ltd | Manufacturing | 2019 |
| Clark Landscapes & Building Ltd | Administrative & support | 2015 |
| Classic Car Revivals Limited | Wholesale & retail | 2019 |
| Clear Lion Ltd | Professional & scientific | 2024 |
| Clearvu Limited | Wholesale & retail | 1998 |
| Clements Music Ltd | Arts & recreation | 2025 |
| Clixilo Ltd | Administrative & support | 2019 |
| Cloud Development Partner Ltd | Information & communication | 2019 |
| CNH Cars Ltd | Wholesale & retail | 2024 |
| Co-Lab Mgmt Limited | Professional & scientific | 2023 |
| Cognition 24 Ltd | Information & communication | 2019 |
| Colclough Game and Sporting Ltd | Agriculture & fishing | 2022 |
| Collaborative Counselling Academy Ltd | Education | 2020 |
| Commercially Wright Limited | Professional & scientific | 2019 |
| Compuclinic Ltd | Information & communication | 2024 |
| Connected Alternative Provision Ltd | Real estate | 2025 |
| Consultants AS a Service Ltd | Administrative & support | 2022 |
| Contactfree Limited | Information & communication | 2015 |
| Cook Better EAT Well Ltd | Education | 2024 |
| Core Alpha Properties Ltd | Real estate | 2021 |
| Corenet Limited | Information & communication | 2015 |
| Cork Management Limited | Agriculture & fishing | 2026 |
| Coventry Gauge Ltd | Manufacturing | 2026 |
| CPI Refrigeration Ltd | Construction | 2015 |
| Creative Coda Ltd | Information & communication | 2019 |
| Creative Conversions Limited | Real estate | 2016 |
| Crest Comms Holdings Ltd | Professional & scientific | 2018 |
| Crest Comms Ltd | Professional & scientific | 2015 |
| Crest Electrical Ltd | Construction | 2022 |
| Crestcove Estates Ltd | Real estate | 2001 |
| Crestel Home Access Limited | Construction | 2009 |