| Automotive Reports Limited | Professional & scientific | 2007 |
| Avalon Space Infrastructure and Services Ltd | Manufacturing | 2023 |
| Aviva Insurance UK Limited | Professional & scientific | 1908 |
| Aviva Ukgi Investments Ltd | Extraterritorial | 1988 |
| Aylin Feltwell Ltd | Hospitality | 2025 |
| B J Wright Limited | Agriculture & fishing | 2003 |
| B.A. Yeomans & SON Limited | Wholesale & retail | 2002 |
| B.F.S. (Electrical Contractors) Limited | | 1986 |
| Balancing ACT (Cambridge) Ltd | Professional & scientific | 2006 |
| Bandkay Enterprises Limited | Wholesale & retail | 2000 |
| Barclay Beales Limited | Wholesale & retail | 1975 |
| Barker Bros. (Downham Market) Group Limited | Professional & scientific | 1969 |
| Barker Bros. (Investment Properties) Limited | Real estate | 1981 |
| Barker Bros. Builders Limited | Real estate | 1969 |
| Barley Chalu Limited | Manufacturing | 1967 |
| Barley HR Ltd | Administrative & support | 2006 |
| Barry Francis Pallets Limited | Professional & scientific | 2003 |
| Bartec Limited | Wholesale & retail | 1986 |
| Baskan 123 Ltd | Hospitality | 2021 |
| Battle Home Improvements Ltd | Construction | 2006 |
| Bawdeswell Farms Limited | Agriculture & fishing | 1952 |
| Baxter Healthcare Limited | Manufacturing | 1948 |
| Baxter International Limited | Manufacturing | 2024 |
| Baxter Medical Limited | Manufacturing | 2024 |
| Beardshaw Bros Limited | Wholesale & retail | 1982 |
| Beatrice of Bristol Limited | Hospitality | 1990 |
| Beauty Brows PVT Ltd | Other services | 2025 |
| Beck Farm Partnership | | 1999 |
| Becs Software Solutions Ltd | Information & communication | 2002 |
| Bed-Down LLP | | 2016 |
| BEN Garrod Limited | Information & communication | 2023 |
| Benthic Solutions Limited | Professional & scientific | 2004 |
| Beond Engineering Ltd | Manufacturing | 2004 |
| BER Street Used Cars Limited | Wholesale & retail | 2016 |
| Berry & Warren Ltd | Professional & scientific | 2007 |
| Bexwell Kitchens Limited | Construction | 1965 |
| Bicotest High Voltage Products Limited | Manufacturing | 2001 |
| Big FRY (Wymondham) Limited | Hospitality | 2005 |
| Biriyani Potlam Ltd | Hospitality | 2025 |
| Birkett Wood Ltd | Arts & recreation | 2026 |
| Birth of a MAN Limited | Arts & recreation | 1980 |
| Black Shuck Properties Limited | Real estate | 2020 |
| Blackburns (Harleston) Limited | Professional & scientific | 1952 |
| Blackfriars (West Norfolk) Limited | Financial services | 1997 |
| Blakeney Residents Association Limited | Households | 1985 |
| Blooms Nurseries Limited | Agriculture & fishing | 1948 |
| Bluebell Rental and Leisure Limited | Hospitality | 2026 |
| Bluewater Inspection Ltd | Mining & quarrying | 1999 |
| Blyth & Wright Limited | Wholesale & retail | 2001 |
| BMR Ventures Ltd | Administrative & support | 2025 |
| BOB Cutter Landscapes Limited | Administrative & support | 2007 |
| Body Concept Fitness by Design Limited | Arts & recreation | 2002 |
| Booters Ltd | Professional & scientific | 1988 |
| Bossretty Limited | Other services | 1976 |
| Brabyn & Berger Limited | Real estate | 1960 |
| Bradenham Hall Farms | | 1987 |
| Brailey's Electrical Ltd | Construction | 2025 |
| Brandon Warehouse Ltd | Real estate | 2026 |
| Brattoncourt Limited | Real estate | 1982 |
| Breckland Conservatories Limited | | 1987 |
| Breckland Healthcare & Mobility Limited | Wholesale & retail | 2007 |
| Breckland Hygiene & Industrial Supplies Limited | Wholesale & retail | 2002 |
| Breckland Organics Limited | Agriculture & fishing | 2007 |
| Brian RIX & SON Limited | Construction | 2002 |
| Bright Rabbit Limited | Administrative & support | 2007 |
| Briningham Farms Limited | Agriculture & fishing | 1998 |
| Britannia House (Hunstanton) Company Limited | Real estate | 2003 |
| British Trust for Ornithology(The) | Professional & scientific | 1939 |
| Broadland Group Limited | Professional & scientific | 1998 |
| Broadland Mobility Limited | Wholesale & retail | 2004 |
| Broadsword Accountancy Ltd | Professional & scientific | 2004 |
| Brolly Limited | Extraterritorial | 2007 |
| Brook HR Ltd | Professional & scientific | 2026 |
| Browick Farm Limited | Agriculture & fishing | 1959 |
| Browick Properties Limited | Construction | 1996 |
| Brown and Flaxman Developments Limited | Construction | 2006 |
| Brybird Homecare Limited | Public administration | 2024 |
| Bucher & Harrison Limited | Other services | 2007 |
| Buildbest Conversions Limited | Construction | 2007 |
| Builders Equipment Direct Limited | Professional & scientific | 2000 |
| Building Integrated Systems Ltd | Construction | 2018 |
| Bulletin Board Systems Limited | Information & communication | 1994 |
| Burbidge's of Norfolk Limited | Wholesale & retail | 2003 |
| Burdess Engineering Limited | Manufacturing | 2006 |
| Bure Buildings Limited | Real estate | 2022 |
| Bure Electrical Co Ltd | Construction | 2005 |
| Burnham Market Stores Limited | Wholesale & retail | 2004 |
| Burridge Kitchens & Bedrooms Ltd | Construction | 2003 |
| Business Books Accounting Limited | Professional & scientific | 2005 |
| Bussey & Sabberton Bros.Limited | Wholesale & retail | 1922 |
| Buyinfo Limited | Energy | 1994 |
| Bwwc Limited | Real estate | 2007 |
| Bywater Farms Ltd | Agriculture & fishing | 2007 |
| C & S Business Services Limited | Professional & scientific | 2006 |
| C J Engineering (Thetford) Limited | Manufacturing | 1998 |
| C P Services (Spalding) Limited | Transport & logistics | 2004 |
| C P Solutions Ltd | Professional & scientific | 2024 |
| C R Masih Company Ltd | Health & social care | 2019 |
| C R Rose Limited | Wholesale & retail | 2007 |
| C S J Properties Limited | Real estate | 2002 |