| Red Hill Farming Company Limited | Milton Keynes | 2004 |
| Red HOG Pastures Limited | Grimsby | 2017 |
| Red House Farm (Lincs) Limited | Marlborough | 2025 |
| Red House Farm Equestrian Ltd | Andover | 2018 |
| Red House Farming | Northallerton | 2011 |
| Red Kite Art and Jewels Limited | Burry Port | 2015 |
| Red Kite Conservation Services Ltd | Frimley Green | 2010 |
| Red Kite Farms Limited | Nr Henley On Thames | 1996 |
| Red Kite Rural Ltd | Eaton Socon, St Neots | 2021 |
| Red Lion Farm Limited | Winchester | 1992 |
| Red Lodge Canine Country Club Limited | Swindon | 2022 |
| Red Monster Ltd | Aylesbury | 2025 |
| Red Oak Farming Limited | Tilton On The Hill | 2026 |
| Red Oak Treecare Ltd | London | 2022 |
| Red Pines Ranch Ltd | Llandeilo | 2025 |
| Red PIT Farm Limited | Norwich | 1973 |
| Red Robin Farm Limited | Dover | 2022 |
| Red Rock Equestrian Limited | Caerphilly | 2025 |
| Red Rock Forestry Limited | Chester | 2019 |
| Red Roofs Nursery Limited | Cottingham | 2003 |
| Red Rose Salads Limited | Southport | 1989 |
| Red Rosette Ltd | Northampton | 2023 |
| Red Ruby Tackle Ltd | London | 2025 |
| Red Sea Fresh Fisheries Ltd | Birmingham | 2023 |
| Red Squirrel Farming Limited | Aberdeen | 2021 |
| Red Squirrel South West Project Limited | Ottery St. Mary | 2010 |
| Red Squirrel Tree Surgery Ltd | London | 2016 |
| Red Stag Group Limited | Burntwood | 2017 |
| Red Star Growers Limited | Worcs. | 1990 |
| Red Tree Landscapes Ltd | Leeds | 2011 |
| Red Wharf Systems Limited | Anglesey | 2001 |
| Red's Equestrian Ltd | Waterlooville | 2025 |
| Redberth Croft CIC | Tenby | 2024 |
| Redbridge Lakes Ltd | Woodford | 2006 |
| Redbrown Limited | Chelmsford | 2020 |
| Redcar Investment Co.Limited | Reading | 1958 |
| Redcastle Farms Limited | By Arbroath | 1943 |
| Redcliffe Kennels Limited | Bristol | 2021 |
| Redcoll Estates Limited | East Lothian | 1983 |
| Redd Carbon & Biodiversity Advisors LLC and Redd Coalition of Partners (UK) Limited | London | 2015 |
| Reddaway Ltd | Crediton | 2012 |
| Reddicap Kennels & Catteries Limited | Middleton | 1959 |
| Redditch Tree Surgeons Limited | Redditch | 2023 |
| Reddog Forestry & Contracting Ltd | Bordon | 2025 |
| Redearth Forestry Ltd | Derby | 2026 |
| Redfearn Farming Limited | Cleckheaton | 2018 |
| Redfern Farming Ltd | Yarlet | 2023 |
| Redford Farms Limited | Forfar | 1993 |
| Redford Flowers Limited | Spalding | 2009 |
| Redgate Bloodstock Limited | Bury St Edmunds | 2008 |
| Redgate Dairy Farm Limited | Guyhirn | 2014 |
| Redgate Farm Animal Sanctuary Limited | Markfield | 2018 |
| Redgate Farming Ltd | Taunton | 2025 |
| Redham Farms Limited | Bungay | 1941 |
| Redhill Farm (Free Range Pork) Limited | Lincolnshire | 2005 |
| Redhill Farm Estate Ltd. | Maidstone | 2015 |
| Redhill Farm Services Ltd | Redhill | 2020 |
| Redhill Farms (Shotley) Limited | Ipswich | 2012 |
| Redhill Farms Limited | Milton Keynes | 2004 |
| Redhouse Castle Limited | Edinburgh | 1994 |
| Redland Tree Services Limited | Portishead | 2021 |
| Redlands Farming Ltd | York | 2025 |
| Redlands Orchard and Gardens Ltd | Swindon | 2021 |
| Redleaf Woodland Management Limited | Peterborough | 2019 |
| Redline Equestrian Limited | Preston Brook | 2019 |
| Redmayne (Brockholes) Limited | Preston | 2006 |
| Redmile Grain Tech Services Ltd | Redmile | 2013 |
| Redpath Fisheries Ltd | Berwick Upon Tweed | 2018 |
| Redricks Leisure Park Limited | Bishop'S Stortford | 2012 |
| Redricks Leisure Services Limited | Bishop'S Stortford | 2013 |
| Redrock Tree Care Ltd | Alton | 2024 |
| Redsikes Eggs Limited | Kendal | 2003 |
| Redswoodland Ltd | London | 2019 |
| Redwall Syndicate Limited | Gloucester | 2016 |
| Redway Maintenance Limited | Harlow | 2020 |
| Redwell Farms Limited | By Forfar | 2009 |
| Redwin Holdings Limited | Cambridge | 1985 |
| Redwings Horse Sanctuary | Norwich | 1998 |
| Redwood 2018 Ltd | Ashby-De-La-Zouch | 2018 |
| Redwood Barn Limited | Wantage | 2019 |
| Redwood Equestrian Ltd | Camberley | 2017 |
| Redwood FUR & Feather Ltd | Reading | 2017 |
| Redwood Tree and Land Services Limited | Leigh-On-Sea | 2020 |
| Redwood Tree Services Limited | Guildford | 2004 |
| Redwood Tree Surgeons Ltd | Guildford | 2008 |
| Redwood Tree Surgery Limited | Bury St Edmunds | 2020 |
| Redwoodagri Ltd | London | 2026 |
| Redwoods Livery (Leven) Limited | Beverley | 2023 |
| Reed Agri Services Ltd | Barnard Castle | 2020 |
| Reed Bloodstock and Racing Limited | Newmarket | 2020 |
| Reed Equestrian Ltd | Haverhill | 2026 |
| Reed Estates Limited | Pickering | 1996 |
| Reedflow Limited | Dunfermline | 1999 |
| Reef Culture Ltd | Leatherhead | 2010 |
| Reef Doctor.Org Limited | Skipton | 2000 |
| Reef Exotics Limited | Colchester | 2017 |
| Reef GRO Limited | Ipswich | 2026 |
| Reef Ranch Publishing Ltd | Leeds | 2022 |
| Reef-Geeks Ltd | Portsmouth | 2016 |
| Reeffreaks Ltd | Barnoldswick | 2024 |