| Robert Milton Limited | Information & communication | 2009 |
| Robert Moss Consulting Limited | Professional & scientific | 2015 |
| Robert Reeds Limited | Extraterritorial | 2026 |
| Robert Sutton Limited | Professional & scientific | 2019 |
| Robert&Isha Art Design Co., Ltd. | Wholesale & retail | 2021 |
| Roberto Automobile Mechanic Ltd | Wholesale & retail | 2025 |
| Roberts & Roberts Limited | Administrative & support | 2017 |
| Roberts & Rowles Properties Limited | Real estate | 2023 |
| Roberts Cardiff Ltd | Wholesale & retail | 2021 |
| Roberts Jewellers Cardiff Ltd | Wholesale & retail | 2021 |
| Roberts Roof Windows Ltd | Construction | 2025 |
| Robertsons Legal Ltd | Professional & scientific | 2015 |
| Robihoo | Professional & scientific | 2024 |
| Robin Hood Parking Ltd. | Administrative & support | 2006 |
| Robin King Architectural Products Limited | Professional & scientific | 2017 |
| Robingoods Ltd | Wholesale & retail | 2026 |
| Robinson Brickwork Cardiff Limited | Construction | 2023 |
| Robinson Building and Surveying Services Limited | Administrative & support | 2019 |
| Robinson Property and Management Group Ltd | Real estate | 2026 |
| Robinson Smith Limited | Wholesale & retail | 2014 |
| Robitrix Ltd | Extraterritorial | 2019 |
| Robkulyn Ltd | Administrative & support | 2019 |
| Robocom UK Limited | Transport & logistics | 2001 |
| Roborant IT Ltd | Information & communication | 2008 |
| Robot Machine Learning Ltd | Information & communication | 2025 |
| Robovia Edge Ltd | Wholesale & retail | 2025 |
| Robs Cars Sales Repairs & Recovery Limited | Wholesale & retail | 2023 |
| Robson Consultants Ltd | Construction | 2012 |
| Robson Reid Wealth Management Limited | Financial services | 2025 |
| Robson Technologies Limited | Information & communication | 2025 |
| Robson&Co. Ltd | Other services | 2019 |
| Roburtree Ltd | Manufacturing | 2021 |
| Robust Belts Ltd | Wholesale & retail | 2025 |
| Robust Technology Limited | Information & communication | 2018 |
| Robyn FOX Property Limited | Real estate | 2022 |
| ROC Cliff Ltd | Financial services | 2025 |
| Roccobar Limited | Hospitality | 2026 |
| Roccoco SŴN Limited | Information & communication | 2023 |
| Rocen Homesteady Ltd | Agriculture & fishing | 2026 |
| Rochay Creative Media Ltd | Information & communication | 2019 |
| Rochay Elite Limited | Professional & scientific | 2005 |
| Rochefort Shugar Limited | Real estate | 2008 |
| Rochelle Corde Ltd | Professional & scientific | 2017 |
| Rochelle Natty Business Group Ltd | Wholesale & retail | 2018 |
| Rock & Malt Limited | Hospitality | 2025 |
| Rock and Roll Star Productions Limited | Education | 2016 |
| Rock Paper Studios Ltd | Information & communication | 2014 |
| Rock Solid Accounting UK Limited | Professional & scientific | 2021 |
| Rock-Ola Holdings Limited | Financial services | 2024 |
| Rockadove Limited | Administrative & support | 2014 |
| Rockall Safety Limited | Real estate | 1999 |
| Rockblock Ltd | Information & communication | 2018 |
| Rockcastle MP Limited | Health & social care | 2006 |
| Rocket Fuel Coffee Company Limited | Manufacturing | 2025 |
| Rocket Joes (Cardiff) Limited | Hospitality | 2018 |
| Rocket Jose Cardiff Ltd | Hospitality | 2026 |
| Rocket Pizza Limited | Hospitality | 2017 |
| Rocket Salad Limited | Information & communication | 2001 |
| Rocket Science Corporation (UK) Ltd | Information & communication | 2022 |
| Rocket Security Limited | Administrative & support | 2012 |
| Rocketmeme Ltd | Information & communication | 2025 |
| Rocketshot Limited | Hospitality | 1998 |
| Rocketworld MX Ltd | Arts & recreation | 2013 |
| Rockfield Vets Limited | Professional & scientific | 2019 |
| Rockgold Ltd | Manufacturing | 2020 |
| Rockman Group Limited | Information & communication | 2024 |
| Rocks Renovations Ltd | Real estate | 2023 |
| Rocksalt Photography LP | | 2008 |
| Rockspan Property Ltd | Real estate | 2023 |
| Rockstar Car Group Ltd | Wholesale & retail | 2022 |
| Rockstar Global Ltd | Administrative & support | 2015 |
| Rocktoprise Ltd | Administrative & support | 2025 |
| Rockwealth Cardiff Ltd | Professional & scientific | 2021 |
| Rockwell Music Group Ltd | Arts & recreation | 2017 |
| Rockwell Printing Machinery PLC | Manufacturing | 1902 |
| Rockwood Property Investors Ltd | Real estate | 2019 |
| Rocky Construction Ltd | Construction | 2018 |
| Rockyblase Holiday Lets Ltd | Hospitality | 2026 |
| Rockyblase Professional Services Ltd | Information & communication | 2026 |
| Rockyblase Property Management Ltd | Households | 2026 |
| Rockyblase Property Services Ltd | Construction | 2026 |
| Rockyblase Real Estates Ltd | Real estate | 2026 |
| Rocman Limited | Extraterritorial | 2021 |
| Rocside Ltd | Wholesale & retail | 2024 |
| Rocsyn Ltd | Administrative & support | 2015 |
| Rodand Property Limited | Real estate | 2012 |
| Roddy Digital Limited | Information & communication | 2021 |
| Rodeo Solutions Ltd | Financial services | 2019 |
| Roderick Maclennan Architects Limited | Professional & scientific | 2007 |
| Rodexo Ltd | Information & communication | 2019 |
| Rodica Wine and Spirits Limited | Wholesale & retail | 2017 |
| Rodina Agricultural UK Ltd | Wholesale & retail | 2024 |
| Rodina BG Limited | Construction | 2019 |
| Rodings Plumbing and Heating Ltd | Other services | 2012 |
| Rodney Supplies Ltd | Wholesale & retail | 2021 |
| Rodopi Contruction Ltd | Construction | 2017 |
| Rodos Group Ltd | Wholesale & retail | 2022 |
| Rodrive Limited | Wholesale & retail | 2023 |
| Rods and Lines Limited | Wholesale & retail | 2017 |
| Rodway Engineering Limited | Construction | 1994 |