| Box TV (in Production) Limited | London | 2004 |
| Box TV (Prodco) Limited | London | 2002 |
| Box TV (Production) Ltd | London | 2002 |
| Box TV (S&L) Limited | London | 2001 |
| Box Twenty Two Limited | Coventry | 2016 |
| Boxair UK Limited | Sutton Coldfield | 2007 |
| Boxbot Limited | Falmouth | 2016 |
| Boxclever Total Waste Management Limited | Burntwood | 2005 |
| Boxed Blinds Limited | Telford | 2018 |
| Boxenvi Ltd | Driffield | 2023 |
| Boxford 2 Limited | Sowerby Bridge | 1983 |
| Boxfort Limited | Stanmore | 2018 |
| Boxfresh Global Limited | | 2005 |
| Boxgraft Steward Limited | Harrow | 2000 |
| Boxilicious Ltd | Leigh | 2021 |
| Boxing Day 365 Limited | Cannock | 2021 |
| Boxly Ltd | Preston | 2026 |
| Boxmoor Estate Ltd | | 2006 |
| Boxmoor Hills UK Ltd | Burnham-On-Crouch | 2003 |
| Boxon Ltd | Southend-On-Sea | 2022 |
| Boxsafe Limited | Newcastle Upon Tyne | 2008 |
| Boxsash Window Factory Ltd | Buckinghamshire | 2012 |
| Boxshifters Ltd | Solihull | 2005 |
| Boxted Cross Management Limited | Colchester | 2019 |
| Boxtick Ltd | Coventry | 2014 |
| Boxtxi Limited | Hatfield | 2017 |
| Boxvue Multimedia Ltd | London | 2017 |
| Boxwood Business Services Limited | Folkestone | 2002 |
| Boxwood Close Limited | Tetbury | 1984 |
| Boxwood Consulting Ltd | Bury | 2021 |
| Boxwood Homes Limited | Tonbridge | 2014 |
| Boxxed Events Ltd | Barnsley | 2025 |
| Boxxstep Ltd | Horsham | 2016 |
| BOY in DA Corner Records Ltd | Haslemere | 2020 |
| Boyce Anderson Motors Limited | Carrickfergus | 1973 |
| Boycott 1967 Limited | Pontefract | 2015 |
| Boyd Properties Limited | Newcastle-Under-Lyme | 2006 |
| Boyd&Boris Ltd | Dartford | 2013 |
| Boydslaw 103 Limited | Dunfermline | 2006 |
| Boyes Manto Ventures Limited | Shepperton | 2025 |
| Boygle Enterprises Ltd. | Stockport | 1996 |
| Boylees Science Limited | Beckenham | 2012 |
| Boylin Commercial Limited | Barnsley | 2013 |
| Boylin Handling Limited | Barnsley | 2018 |
| Boylin's Selfstore (Barnsley) Limited | Barnsley | 2013 |
| Boylin's Selfstore (Carlton) Limited | Barnsley | 2018 |
| Boylin's Selfstore (Sheffield) Limited | Barnsley | 2013 |
| Boylin’S Selfstore (Agbrigg Road) Limited | Barnsley | 2021 |
| Boyne Bay Lime Company Ltd. (the) | Monifieth | 1944 |
| Boys and Maughan Solicitors Ltd. | Kent | 2005 |
| Boys' and Girls' Welfare Society Limited | Cheadle | 2005 |
| Boys-R-Us Limited | Berkshire | 2004 |
| Boyu Hardware Co., Ltd | London | 2014 |
| Boyu Technology Co., Ltd | Stafford, | 2020 |
| Bozzo Brasil Trading Limited | Canvey Island | 1985 |
| BP (Essex) Ltd | Leigh-On-Sea | 2018 |
| BP (Langdon) Ltd | Leigh-On-Sea | 2019 |
| BP Concrete Flooring Limited | Belfast | 1973 |
| BP Corporate Ltd | Lisburn | 2024 |
| BP Fitness Limited | Thatcham | 2022 |
| BP Online Ltd | Swansea | 2024 |
| BP Wealth Ltd | Horsham | 2016 |
| BP Yachting Ltd | London | 2024 |
| BP24 Digital Media Limited | Wakefield | 2018 |
| BPA Vacuum Pumps Limited | Leeds | 2004 |
| BPB Finance (NO.6) | Leicestershire | 2003 |
| BPB Paperboard Limited | Glasgow | 1959 |
| BPC Partners Group Ltd | Cheltenham | 2009 |
| BPC Pest Control Ltd | Romford | 2016 |
| BPC Roofing Limited | Romford | 2020 |
| Bpclx Limited | Chippenham | 2010 |
| BPF Blackball | Dumfries | 2026 |
| BPI General Partner Limited | Paisley | 2010 |
| BPK Property Limited | Belfast | 2014 |
| BPM Cleaning and Maintenance Ltd | Sevenoaks | 2021 |
| BPM Media (Midlands) Limited | London | 1971 |
| BPM Ventures Ltd | Manchester | 2024 |
| Bpmt Growth Strategy Limited | Billericay | 2016 |
| BPO Law Limited | Rochdale | 2024 |
| BPO Respect Ltd | Ardrossan | 2019 |
| Bppm Consulting Limited | Poole | 2018 |
| BPR Group Europe Ltd | London | 2019 |
| BPR Heaton Limited | Leeds | 2022 |
| BPS Co. (Properties) Ltd | Stratford-Upon-Avon | 2022 |
| BPS Windows and Doors Ltd | Newton Abbot | 2025 |
| Bpsl Limited | Benfleet | 2022 |
| BPT (Full Reversions) Limited | Gateshead | 2001 |
| BPT Electrical Ltd | Belfast | 2014 |
| Bpteot Limited | Kington | 2022 |
| BQ Ltd | Newmarket | 2020 |
| BQS Certification Limited | Milton Keynes | 2014 |
| BR DLL Limited | Teddington | 1979 |
| BR Investment Norway Limited | London | 2011 |
| BR Konsult O Utbildningar Limited | London | 2023 |
| BR Legal Consultancy Ltd | Thornton-Cleveleys | 2021 |
| BR LEY 3 Limited | Leytonstone | 2020 |
| BR LEY 6 Limited | Leytonstone | 2020 |
| BR LEY 8 Limited | Leytonstone | 2020 |
| BR Trustees Limited | London | 2008 |
| Br!Ck Limited | London | 2024 |