| Boost Recruitment Ltd | Administrative & support | 2014 |
| Bored? Limited | Wholesale & retail | 1996 |
| Bounceback Marketing Limited | Professional & scientific | 2023 |
| Bountiful Properties Limited | Real estate | 2018 |
| Bower House Management Limited | Extraterritorial | 2008 |
| Bowerman Bros Limited | | 1957 |
| Braddock Software Limited | Information & communication | 2024 |
| Bramwell Limited | Hospitality | 1998 |
| Brandtech Design Ltd | Construction | 2017 |
| Brandtech Signs Ltd | Construction | 2021 |
| Brangier Business Development Ltd | Information & communication | 2023 |
| Brankesmere Ltd | Information & communication | 2018 |
| Brankesmere Terrace Management Limited | Households | 2005 |
| Bransbury Park Butchers Ltd | Wholesale & retail | 2022 |
| Bread Addiction Limited | Wholesale & retail | 2014 |
| Break Point Services Limited | Administrative & support | 2025 |
| Brent Court Limited | Households | 2009 |
| Brialex Construction Ltd | Construction | 2016 |
| Brickteck Limited | Construction | 2024 |
| Bright Life Properties Limited | Real estate | 2005 |
| Brighter Still Limited | Professional & scientific | 2026 |
| Brightsfield Portfolio Limited | Financial services | 2006 |
| Brind Telecoms Limited | Professional & scientific | 2012 |
| Britannia Court Management Limited | Real estate | 2018 |
| Broadsword Developments Ltd | Construction | 2023 |
| Broadway Coffee Roasters Ltd | Manufacturing | 2020 |
| Broadway Collective Group Limited | Financial services | 2026 |
| Brooks Drywall Systems Ltd | Construction | 2016 |
| Brookson (5332I) Limited | Information & communication | 2007 |
| Bruce Road Management Company Limited | Households | 1979 |
| Brunels Limited | Extraterritorial | 2006 |
| Bruni Investments Limited | Real estate | 2022 |
| Brushstrokes Painting and Decorating Services Limited | Construction | 2025 |
| Brwny Ltd | Information & communication | 2019 |
| BSF Holdings Ltd | Financial services | 2018 |
| Bsure TLS Ltd | Real estate | 2015 |
| BT Gifts Ltd | Wholesale & retail | 2023 |
| BTG Label Limited | Wholesale & retail | 2025 |
| Bubblehead Barista Ltd | Manufacturing | 2020 |
| Buckman Consultancy Ltd | Professional & scientific | 2021 |
| Bucknall & Bucknall Property Ltd | Real estate | 2024 |
| Buckwells Freehold Ltd | Real estate | 2020 |
| Build & Refurb Associates Limited | Construction | 2011 |
| Build & Refurb Management and Consult Ltd | Construction | 2020 |
| Built Environment Consultants Limited | Professional & scientific | 2008 |
| Bunkus Tea | | 2009 |
| Burlington Court Sholing Limited | Other services | 2007 |
| Business Builders (South) Ltd | Information & communication | 2018 |
| Business Protection Expert Ltd | Financial services | 2014 |
| Business Systems Solutions Limited | Information & communication | 1994 |
| Bustle and Bertie Ltd | Wholesale & retail | 2020 |
| Busy Mama Limited | Information & communication | 2019 |
| Buy the Hub Ltd | Wholesale & retail | 2025 |
| Buyaiglobal Limited | Information & communication | 2025 |
| BY Cherry Media Ltd | Information & communication | 2025 |
| BY the Beach Southsea Ltd | Education | 2020 |
| Byngs Autos Limited | Wholesale & retail | 2010 |
| C a Silver Lining Ltd | Construction | 2015 |
| C Slater DRY Lining Ltd | Construction | 2016 |
| C Wilkins Construction Ltd | Professional & scientific | 2014 |
| C.R. Barrow & Associates Limited | Professional & scientific | 2013 |
| Caboom Productions Limited | Information & communication | 2017 |
| Cake Dealer Ltd | Manufacturing | 2025 |
| Caldararu Prestige Cleaning Limited | Administrative & support | 2026 |
| Calder Bricklaying Contractors Ltd | Construction | 2007 |
| Calhoun Square Ltd | Real estate | 2020 |
| Camera Crate Limited | Wholesale & retail | 2020 |
| Cameron & Associates (Insurance Services) Limited | Financial services | 1997 |
| Cameron Asset Management Limited | Financial services | 2005 |
| Cameron Jewellers Trading AS Young George Jewellers Limited | Wholesale & retail | 2025 |
| Camma Sport Ltd | Wholesale & retail | 2026 |
| Campbell Property Limited | Households | 2001 |
| Campbell Road Company Limited | Real estate | 1993 |
| Cams Homes & Apartments Ltd | Real estate | 2024 |
| Canary Lettings and Property Management Limited | Real estate | 2019 |
| Canteen Coffee Ltd | Administrative & support | 2016 |
| CAP Interiors Ltd | Construction | 2025 |
| Car Clean & Go Ltd | Administrative & support | 2021 |
| Car Exchange Limited | Wholesale & retail | 2024 |
| Car Park Wash & Valeting Ltd | Administrative & support | 2021 |
| Cardinham Coaching Ltd | Professional & scientific | 2023 |
| Carehub Portsmouth Ltd | Health & social care | 2024 |
| Caribbean Styles Ltd | Wholesale & retail | 2023 |
| Carioca Emporio Ltd | Wholesale & retail | 2021 |
| Carl Architect Ltd | Professional & scientific | 2006 |
| Carl Design Ltd | Professional & scientific | 2025 |
| Carl Marsh Building Services Limited | Construction | 2022 |
| Carlton Premium Products UK Ltd | Information & communication | 2015 |
| Carmen Court Limited | Households | 2017 |
| Carnation Properties Ltd | Real estate | 2020 |
| Carole Chantler Limited | Professional & scientific | 2016 |
| Carp Carpentry Limited | Construction | 2019 |
| Carter Gold Limited | Professional & scientific | 1998 |
| Casa DO SOL Limited | Arts & recreation | 2025 |
| Casa Southsea Limited | Hospitality | 2025 |
| Castaway Carpentry Ltd | Construction | 2023 |
| Castle & Echelon Accountants Ltd | Professional & scientific | 2019 |
| Catdent Limited | Health & social care | 2022 |
| Cave Academy Online Ltd | Information & communication | 2019 |
| Cavewell Holdings Ltd | Real estate | 2026 |