| Riva Media Limited | Professional & scientific | 2013 |
| Rival Content Ltd | Information & communication | 2020 |
| River 52 Limited | Real estate | 2021 |
| River Ocean Limited | Professional & scientific | 2003 |
| Riverside Yard Limited | Real estate | 2025 |
| Riviera Developments Limited | Construction | 2025 |
| Rixan Commercials Limited | Wholesale & retail | 2026 |
| RJB Accountancy Limited | Professional & scientific | 1987 |
| RJB2 Consulting Ltd | Professional & scientific | 2024 |
| Rjco IT Services Ltd | Information & communication | 2021 |
| Rjds 1 Ltd | Real estate | 2022 |
| RJT Land Ltd | Real estate | 2022 |
| RK TZ Ltd | Real estate | 2021 |
| RKL Electrical South Limited | Construction | 2019 |
| RKL Electrical Southern Contractors Limited | Wholesale & retail | 2022 |
| RLG Consultancy Services Limited | Professional & scientific | 2009 |
| Rlol Dental Limited | Health & social care | 2022 |
| Rlol Family Limited | Financial services | 2023 |
| Rlol Letting Ltd | Real estate | 2020 |
| Rlpt Code Ltd | Professional & scientific | 2025 |
| RM Insight Ltd | Professional & scientific | 2010 |
| RM35 Limited | Health & social care | 2020 |
| RMA Psychological Services Limited | Health & social care | 2015 |
| RMC Sussex Ltd | Real estate | 2023 |
| RML Architecture Limited | Administrative & support | 2007 |
| Ro&Ze Ltd | Construction | 2025 |
| Road Nomad Limited | Information & communication | 2025 |
| ROB Petherick Ltd | Professional & scientific | 2004 |
| Robert Clare Business Consulting Ltd | Professional & scientific | 2014 |
| Robert Young Ltd | Information & communication | 2011 |
| Robertson Coaching Ltd | Administrative & support | 2024 |
| Robin Court (Yalding Road) Limited | Households | 2018 |
| Robin Hood Health Foundation | Health & social care | 2016 |
| Robin Vincent Learning and Evaluation Ltd | Other services | 2018 |
| Robins Consulting Ltd | Professional & scientific | 2021 |
| Robson Lister Limited | Financial services | 2012 |
| Roca Medical Ltd | Administrative & support | 2014 |
| Roche Barrett Estate Maintenance Ltd | Construction | 2018 |
| Rochester Court Freehold Limited | Real estate | 2022 |
| Rock N Yogi Adventures Ltd | Arts & recreation | 2024 |
| Rocks and Blonds Ltd | Other services | 2023 |
| Rocksea Beauty & Foot Health Ltd | Other services | 2024 |
| Rockwater Group Ltd | Hospitality | 2019 |
| Rockwater Holdings Limited | Financial services | 2024 |
| Rockwater Sandbanks & Branksome Limited | Hospitality | 2021 |
| Rockwater South Coast Limited | Hospitality | 1963 |
| Rodeo Global Ltd | Professional & scientific | 2023 |
| Roecliffe Developments Ltd | Construction | 2021 |
| Roecliffe Equestrian Ltd | Arts & recreation | 2023 |
| Roge Systems Limited | Transport & logistics | 2013 |
| Roger Martin Carpets and Flooring Limited | Construction | 2004 |
| Rogerson Consultancy Ltd | Administrative & support | 2026 |
| Rogerson Investment Limited | Real estate | 2019 |
| ROK Investments (Brighton) Ltd | Real estate | 2023 |
| Rokesley House Limited | Households | 2006 |
| Roland Stevenson Limited | Professional & scientific | 2012 |
| Rolf Berryman Operations Limited | Administrative & support | 2019 |
| Rolleston Solar Farm Limited | Energy | 2014 |
| Roma Investments (Brighton) Ltd | Financial services | 2021 |
| Roma Investments LLP | | 2013 |
| Roman Karl Ltd | Real estate | 2014 |
| Roman Oak Developments Limited | Construction | 2010 |
| Romano Consultancy Services Limited | Financial services | 2020 |
| RON Ansell's PUB Company Ltd | Hospitality | 2013 |
| Ron's Food Ltd | Hospitality | 2020 |
| Rondon Property Ltd | Real estate | 2021 |
| Ronn Ltd | Real estate | 2018 |
| Ronnies Homes Ltd | Real estate | 2021 |
| Root One Dental Ltd | Health & social care | 2018 |
| Roots Nature Therapy CIC | Education | 2026 |
| Ropeysound Limited | Information & communication | 2011 |
| Rosco Painting & Decorating Ltd | Construction | 2022 |
| Rose and Wren Property Ltd | Real estate | 2021 |
| Rose B Advisory Ltd | Real estate | 2022 |
| Ross Renovation Limited | Administrative & support | 2013 |
| Rosulz Resourcing Ltd | Administrative & support | 2025 |
| Rotana Global Foods Ltd | Wholesale & retail | 2026 |
| Rotary Lodge RTM Company Limited | Households | 2025 |
| Rothbury Mews Management Limited | Households | 2013 |
| Rottingdean Dental Care Limited | Health & social care | 2009 |
| Rottingdean Hall Limited | Arts & recreation | 1982 |
| Rotunda Cafe Bar Ltd | Hospitality | 2025 |
| Roundberry Construction Ltd | Construction | 2005 |
| Roundberry Limited | Real estate | 2014 |
| Roundhurst Holdings Limited | Real estate | 2001 |
| Roundstone Finance Limited | Administrative & support | 1995 |
| Rove Create Limited | Manufacturing | 2023 |
| Roviant Limited | Households | 1994 |
| ROW Z Sports Group Ltd | Arts & recreation | 2026 |
| Rowe & Co Property Limited | Real estate | 2010 |
| Rowe Property Services Limited | Financial services | 2005 |
| Rowland SME Business Consulting Ltd | Professional & scientific | 2021 |
| ROX Life (MS) Ltd | Arts & recreation | 2023 |
| ROX Life Ltd | Arts & recreation | 2018 |
| ROY James Martin Bespoke Woodcarving Ltd | Manufacturing | 2021 |
| Royal Oak Country Park Development Limited | Construction | 2008 |
| Royal Oak Country Park Limited | Construction | 2008 |
| RP Roofing Services Ltd | Construction | 2024 |
| RP Smiles Limited | Financial services | 2021 |
| Rpgsh Limited | Real estate | 2021 |