| Busy ME BEE Ltd | London | 2025 |
| Busy Retail Limited | Dorset | 2006 |
| Busy Secretary Service Limited | Cardiff | 2022 |
| Butch 1959 Limited | Dunfermline | 2014 |
| Bute 65 Limited | Gourock | 2014 |
| Buth Bheag Candle Co Ltd | Outer Hebrides | 2015 |
| Butifarra Limited | Blandford Forum | 1997 |
| Butik Wiki ( Italian Fashion ) Ltd | Nottingham | 2015 |
| Butler Fenton Limited | Harrogate | 2025 |
| Butler Fuels Limited | Birchwood | 2011 |
| Butler Holdings Limited | Birmingham | 2015 |
| Butler Sherborn (SAM Butler) Limited | Cirencester | 2014 |
| Butler Windsor Limited | Belper | 1999 |
| Butlers 1960 Limited | King'S Lynn | 2014 |
| Butlers CT Lechlade Limited | Faringdon | 2026 |
| Butlers Wharf Management Company Limited | | 2005 |
| Butlers Yard (Head Lease) Limited | London | 2015 |
| Butlers Yard Freehold Limited | London | 2015 |
| Butley Medical Services Ltd | Butley Low Corner | 2014 |
| Butovo Dynamics Ltd | Harrow | 2024 |
| Butt and Scholes Limited | Knutsford | 2025 |
| Butter & Beyond Ltd | London | 2024 |
| Butter Clocktower Park Ltd | London | 2021 |
| Butter Solutions Limited | Whitchurch | 2026 |
| Butterbur & Sage International Public Limited Company | Reading | 1995 |
| Buttercrumb Bakery Ltd | Doncaster | 2026 |
| Buttercup Homes & Lettings Ltd | Darlington | 2017 |
| Buttercup Investments Limited | Stockport | 2014 |
| Buttercup Technology Ltd | Southport | 2012 |
| Buttercupbelles Limited | Leicester | 2016 |
| Butterfield Street 1959 Limited | Liverpool | 2014 |
| Butterflies Playgroup Ltd | London | 2020 |
| Butterfly & the BEE Ltd | Manchester | 2025 |
| Butterfly and Blackberry Publishing Ltd | Manchester | 2025 |
| Butterfly Brunch Ltd | Cardiff | 2020 |
| Butterfly Castle Day Nursery Limited | Ashby-De-La-Zouch | 2025 |
| Butterfly Data Trustees Limited | Cardiff | 2021 |
| Butterfly Haven CIC | London | 2024 |
| Butterfly Nominee Co Ltd | Altrincham | 2021 |
| Butterfly Transfers Limited | Braintree | 2013 |
| Buttergrove Housing Limited | Bristol | 2020 |
| Butterley Aggregates Limited | Coventry | 1966 |
| Butterley Brick Limited | Northampton | 2016 |
| Buttermilk Falls Investments Limited | Preston | 2007 |
| Butterwood Enterprises Limited | Hook | 2002 |
| Butterworth Property Services Limited | Carlisle | 2014 |
| Butterworths Accountants (North Wales) Limited | Conwy | 2013 |
| Butterworths Accountants Limited | Llandudno | 2004 |
| Butterworths Law Limited | Sheffield | 2014 |
| Buttons & Bows Ltd | Manchester | 2003 |
| Buttons Bear and Friends Limited | Croydon | 1979 |
| Buttons Property Management Limited | Milton Keynes | 2008 |
| Buttress EOT Limited | Manchester | 2025 |
| Buxton Close 1963 Limited | Walsall | 2014 |
| Buxton Lime and Cement Limited | Birmingham | 1919 |
| Buxton Lime Industries Limited | Birmingham | 1991 |
| Buxton Ryan & Co Ltd | Brentwood | 2015 |
| Buy - a - Bike Limited | Lancashire | 1995 |
| Buy 2 Rent Limited | Southend-On-Sea | 2010 |
| Buy Clay Tiles Ltd | London | 2024 |
| Buy Cupa Slate Ltd | Colindale | 2021 |
| Buy From China NOW Limited | Canvey Island | 2020 |
| Buy Insulation Online Ltd | London | 2020 |
| Buy ME Bathrooms Limited | Somerset | 2006 |
| Buy OFF Peak Limited | Colchester | 2000 |
| Buy One GET One Free Limited | London | 2012 |
| Buy Paint Direct Limited | Cirencester | 2022 |
| Buy Roofing Slate Ltd | Colindale | 2021 |
| Buy Samaca Slate Ltd | Colindale | 2021 |
| Buy Slates Ltd | Colindale | 2021 |
| Buy Sofas Direct Limited | Rowley Regis | 2013 |
| Buy Spanish Slate Ltd | Colindale | 2021 |
| Buy the Weigh Ltd | Wadhurst | 2020 |
| Buy to LET Club Limited | Altrincham | 2014 |
| Buy to LET Finance Limited | Bury | 2008 |
| Buy to LET Insurance Services Limited | Guildford | 2003 |
| Buy Tyres Ltd | Colchester | 2011 |
| Buy Tyres Online Limited | Scarborough | 2013 |
| Buy UK Products Limited | Uckfield | 2020 |
| Buy Weekly Limited | London | 2002 |
| Buy-Rite Bi-Folds Limited | Dudley | 2012 |
| Buyadigger Limited | Rochester | 2014 |
| Buyamotorhome Ltd. | Southampton | 2009 |
| Buyer Ltd | London | 2002 |
| Buyers and Sellers Ltd | Ruislip | 2011 |
| BUYIN2IT.CO.UK Limited | Manchester | 2011 |
| Buying Butler Ltd | Nottingham | 2012 |
| Buying for HER Limited | Watford | 2012 |
| Buyituk.Co Limited | Loughborough | 2011 |
| Buymyi Ltd | Haverhill | 2013 |
| Buyon Investment Limited | London | 2025 |
| Buyon Limited | London | 2025 |
| Buyrite Bathrooms Limited | Edinburgh | 1995 |
| Buyukparts Limited | Preston | 2025 |
| Buywell Limited | Ilford | 1995 |
| Buyzo Ltd | London | 2024 |
| Buzby Marketing Limited | Brigthon | 2024 |
| Buzhoushan Industrial Co., Ltd | Kington | 2021 |
| Buzz Bingo Group Limited | Nottingham | 2018 |
| Buzz Design Limited | Yorkshire | 2006 |