| Rektron Earth Ltd | London | 2025 |
| Reliant Nickel Limited | Hertford | 2021 |
| REM 777 Ltd | St. Andrews | 2024 |
| REM Advisory Limited | Marlborough | 2021 |
| Remote Measurement Systems Limited | Aberdeen | 1998 |
| Remote Robotics Ltd | Wellington | 2017 |
| Remote Site Solutions Limited | London | 2017 |
| Remote Solutioneering Limited | Aboyne | 1997 |
| Remote Systems Solutions Ltd. | Aberdeen | 2004 |
| Remote Technology Support Limited | Norwich | 2008 |
| Remson INT Ltd | Kings Hill | 2022 |
| Rendm Ltd | Peterborough | 2019 |
| Rene Trading Limited | Kenilworth | 2024 |
| Renewable Energy Subsea Services Limited | Hartlepool | 2011 |
| Renewearth Technologies Ltd | London | 2024 |
| Renner M&E Ltd | London | 2016 |
| Renny Marine Limited | Halifax | 2024 |
| Renuwell Limited | Maidstone | 2025 |
| Reoc Ltd | Redcar | 2024 |
| Repco Services Ltd | London | 2013 |
| Repton Restoration Limited | Nr Matlock | 2007 |
| Requip Supplies Limited | Coalville | 1991 |
| RES Engg Resources Limited | Warrington | 2021 |
| RES Insights Ltd | Bracknell | 2024 |
| Rescicler Ltd | Falmouth | 2025 |
| Reseng Consultants Ltd | Bonnyrigg | 2014 |
| Reservoir Engineering Solutions Limited | Weybridge | 2021 |
| Reservoir Petrophysics Limited | Brechin | 2018 |
| Residual Anomaly Limited | Wetherby | 2025 |
| Resman Technology UK Ltd | Aberdeen | 2025 |
| Resman Wireless Reservoir Surveillance UK Ltd | Westhill | 2012 |
| Resolute Corporate Services UK Limited | London | 2010 |
| Resolute UK 1 Limited | London | 2019 |
| Resolute UK 2 Limited | London | 2019 |
| Resolve Mining Solutions United Kingdom Limited | London | 2022 |
| Resource Engineering Limited | Altrincham | 1978 |
| Resource Revolution Group Limited | Harrow | 2025 |
| Responsible Mining Company Limited | London | 2024 |
| Restbay Geoscience Ltd | Epsom | 2025 |
| Reswell Integrated Solutions Limited | Aberdeen | 2024 |
| Retfarg Limited | Arbroath | 2025 |
| Retic Systems Ltd | Chepstow | 2023 |
| Reuss Subsea Limited | Lossiemouth | 2011 |
| Rever Offshore International Limited | Leeds | 2010 |
| Revive Intra Limited | Aberdeen | 2015 |
| RF Aggregates Limited | Stoke On Trent | 2008 |
| RFI Services Limited | Blackpool | 2017 |
| RFL Drilling Consultants Limited | Hereford | 2014 |
| RG Stone Supplies Ltd | Elland | 2024 |
| RGB Process & Pipeline Services Ltd | Montrose | 2019 |
| RGK Roofing Ltd | Boston | 2025 |
| RGL Trade Co., Limited | London | 2023 |
| RGM Construction Ltd | Ballymena | 2012 |
| RGP Well Solutions Limited | Aberdeen | 2011 |
| Rhaetian Ltd | Montrose | 2013 |
| RHG Energy Advisory (UK) Limited | Cambridge | 2022 |
| Rhino Minerals Limited | London | 2024 |
| Rhminegeo.Tech Ltd | Derby | 2024 |
| Rich Ernest Ltd | London | 2020 |
| Rich Vein Consulting Limited | Lichfield | 2009 |
| Richard Oxlade Consultancy Ltd. | Aberdeen | 2008 |
| Richardson's Inspection Services Limited | Tunbridge Wells | 2018 |
| Richmal-Agar Limited | Shirley Croydon | 2002 |
| Richrocks Holdings Limited | Birmingham | 2025 |
| Rick Welltech Limited | Aberdeen | 2025 |
| Riddles Bros Limited | Belfast | 2004 |
| Rider Hunt International Limited | Knutsford | 1988 |
| Riduna Metal Resources Limited | London | 2024 |
| RIG & Lift Limited | Blackpool | 2014 |
| RIG Corp Ltd | Plymouth | 2021 |
| RIG Installations Limited | London | 2022 |
| RIG Mover Ltd | Perth | 2018 |
| RIG Ropes Ltd | Clevedon | 2024 |
| RIG Services Limited | Mansfield | 1990 |
| RIG Subsea Limited | Brechin | 2014 |
| Rigby Engineering Solutions Ltd | Norwich | 2015 |
| Rigdeluge Global Limited | Aberdeen | 2012 |
| Rigdeluge Limited | Aberdeen | 2012 |
| Rigel Design Services Ltd | Westhill | 2007 |
| Rigel Petroleum (NI) Limited | 50 Bedford Street | 1995 |
| Rigel Petroleum UK Limited | London | 1997 |
| Rigg Access Limited | Choppington | 1997 |
| Rigging & Haulage Solution's Ltd | Wallsend | 2022 |
| Rigging and Ropes Limited | Stonehaven | 2022 |
| Riggxon Ltd | Bournemouth | 2019 |
| Rigmar Services Limited | Aberdeen | 2007 |
| Rigon Exploration Limited | St. Albans | 2019 |
| Rigon Operations Limited | St. Albans | 2020 |
| Rigpro Consulting Ltd | Ruislip, | 2024 |
| Rigseil Limited | Skipton | 2011 |
| Rigtech Inspection Limited | Newcastle Upon Tyne | 2025 |
| Rigtel Ltd | Ramsgate | 2013 |
| Rigvent Ltd | Glenrothes | 2023 |
| RIO Ashanti UK Limited | London | 2025 |
| RIO Tinto Bauxite Atlantic Limited | London | 2026 |
| RIP Chem ENG Services Limited | Surrey | 2007 |
| Ripple Minerals Ltd | Upton On Severn | 2002 |
| Rise Access Ltd | London | 2025 |
| Rise UP (UK) Limited | Inverurie | 1993 |
| Rising Star Copper Ltd | London | 2018 |